Illegal immigration to the United States

Immigration to the United States in violation of US law

Foreign nationals (aliens) can violate US immigration laws by entering the United States unlawfully Estimates in 2016 put the number of illegal immigrants at 10.7 million, representing 3.3% of the total U. S. population. Since 2007, visa overstays have accounted for a larger share of the growth in the illegal immigrant population than illegal border crossings, which have declined considerably from 2000 to 2018. In 2012, 52% of illegal immigrants were from Mexico, 15% from Central America, 12% from Asia, 6% from South America, 5% from the Caribbean, and another 5% from Europe and Canada. Some argue that illegal immigrants should instead enter the United States lawfully through legal immigration. Research shows that illegal immigrants increase the size of the U. S. economy, contribute to economic growth, enhance the welfare of natives, contribute more in tax revenue than they collect, reduce American firms' incentives to offshore jobs and import foreign produced goods, and benefit consumers by reducing the prices of goods and services. Foreign born non citizens with current status to reside and/or work in the U. S. (documented)
Foreign born non citizens without current status to reside and/or work in the U. S. (illegal)
Foreign born non citizens who are prohibited from entry (illegal and also inadmissible)

The latter two constitute illegal immigrants: as they have no legal documentation to entitle them to be in the U. S., they are also referred to as undocumented immigrants or undocumented Americans. Non citizen residents can be or become illegal in one of four ways: by unauthorized entry, by failure of the employer to pay worker documentation fees, by staying beyond the expiration date of a visa or other authorization, or by violating the terms of legal entry.

Since the late 19th century, various Supreme Court rulings established the Constitutional rights of illegal immigrants. In Yick Wo v. Hopkins (1886), the court ruled that under the Fourteenth Amendment, all people, regardless of "race, of color, or of nationality" have the right to due process and equal protection under the law. A similar ruling of Wong Wing v. U. S. (1896) stated that all persons within the territory of the United States are afforded equal protections under the Fifth Amendment and Sixth Amendment. A 1904 court decision defined any alien as lacking Constitutional rights when not within the United States.

The Naturalization Act of 1906, required immigrants to learn English in order to become citizens. The Immigration Act of 1917 defined aliens with a long list of undesirables, including most Asians. The U. S. had otherwise nearly open borders until the early 20th century, with only 1% rejected from 1890 to 1924, usually because they failed the mental or health exam. While immigration laws during those years were loose, laws limiting naturalization to those of "white" and "African" meant many other immigrants had difficulty acquiring citizenship. These regulations immediately created problems of interpretation – the contentious question of who was and was not "white" vexed even the officials charged with enforcing the law and led to significant criticism. The Union of American Hebrew Congregations noted that under the standing interpretation that Turks, Syrians, Palestinians and Jews were not white, "even Jesus of Nazareth himself" would be excluded from citizenship. As a result, judges and immigration officials often admitted and naturalized technically ineligible people as a form of protest against the laws. The Immigration Act of 1924 established visa requirements and enacted quotas for immigrants from specific countries, especially with low quotas for Southern and Eastern Europeans,. It also prohibited virtually all Asians from immigrating to America. By 1940, administrative and legislative action had loosened racial restrictions on naturalization of immigrants, including a ruling that Mexicans were considered white for immigration and naturalization purposes, and a law permitting the naturalization of "descendants of races indigenous to the Western Hemisphere." The Immigration and Nationality Act of 1965 abolished the quota system. The 1965 Act also established several new limits to which immigrants would be admissible for permanent residence in the United States. A 1990 act increased the annual immigrant limit to 675,000 per year. In 1996, Congress debated two immigration bills one focused on limiting legal immigration, and another focused on illegal immigration. The legal immigration reform bills failed to pass, while the illegal immigration bill was passed in the form of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996. President Bill Clinton signed the Act into law and it became effective on April 1, 1997. The key components of the Act included increasing the number of border agents, increasing penalties on those who assisted illegal immigrants into the United States, creating a 10 year re entry ban on those who had been deported after living in the U. S. illegally for over one year, and expanding the list of crimes that any immigrant (regardless of legal status) could be deported for.

As early as 1904, mounted border watchmen were employed by the U. S. Immigration Service to prevent illegal southern border crossings. Texas Rangers were also often employed along the Texas border with Mexico. Increased border militarization in the United States had the unintended consequence of increasing illegal immigration to the United States, as temporary undocumented immigrants who entered the United States seasonally for work opted to stay permanently in the United States and bring their families once it became harder to move across the border regularly. The U. S. Border Patrol was also officially created in 1924, with its duties in 1925 broadened to include guarding the sea coast. Illegal entry into the United States became a particular problem during Prohibition, when bootleggers and smugglers would illegally enter the country to transport alcohol. During his election campaign, Trump promised to make Mexico pay for a new border wall. The Mexican government refused to do so, and U. S. taxpayers paid for the wall. The federal government entered a partial shutdown from December 22, 2018, to January 25, 2019 in a standoff over Trump's demand for $5.7 billion in funding for the wall.

In 2012, an estimated 14 million people live in families in which the head of household or the spouse is in the United States without authorization. Narrowing the discussion to only Mexican nationals, a 2015 study performed by demographers of the University of Texas at San Antonio and the University of New Hampshire found that immigration from Mexico; both legal and illegal, peaked in 2003 and that from the period between 2003 and 2007 to the period of 2008 to 2012, immigration from Mexico decreased 57%. The dean of the College of Public Policy of the University of Texas at San Antonio, Rogelio Saenz, states that lower birth rates and the growing economy in Mexico slowed emigration, creating more jobs for Mexicans. Saenz also states that Mexican immigrants are no longer coming to find jobs but to flee from violence, noting that the majority of those escaping crime "are far more likely to be naturalized U. S. citizens". According to a 2017 National Bureau of Economic Research paper, "The number of undocumented immigrants has declined in absolute terms, while the overall population of low skilled, foreign born workers has remained stable. because major source countries for U. S. immigration are now seeing and will continue to see weak growth of the labor supply relative to the United States, future immigration rates of young, low skilled workers appear unlikely to rebound, whether or not U. S. immigration policies tighten further."

The Pew Hispanic Center determined that according to an analysis of Census Bureau data about 8 percent of children born in the United States in 2008—about 340,000—were offspring of illegal immigrants. (The report classifies a child as offspring of illegal immigrants if either parent is unauthorized.) In total, 4 million U. S. born children of illegal immigrant parents resided in this country in 2009. These infants are, according to the longstanding administrative interpretation of the Fourteenth Amendment to the United States Constitution, United States citizens from birth. Congress has never legislated, nor the Supreme Court specifically ruled on whether babies born to visiting foreign nationals are eligible for automatic U. S. Citizenship. These children are sometimes referred to as anchor babies because of the belief that the mother gave birth in the United States as a way to anchor their family in the U. S. The provisions of the 1996 immigration law mean that an undocumented parent of a citizen child who entered the country without permission ("illegal entry") would need to leave the United States and wait a number of years before they would be able to apply for a visa to return to the U. S. or gain legal residency on the basis of family reunification, while undocumented parents who legally entered the United States (for example overstaying a visa) can in some cases be sponsored by their adult citizen child for legal residency without necessarily having to leave the country. Additionally, households headed by an undocumented parent are not eligible for many public assistance programs (ex. not eligible for TANF or temporary cash assistance to families with children in extreme poverty, "Obamacare" subsidies for health insurance or expanded Medicaid to working age low income adults, public housing, Section 8 housing voucher program) regardless of whether their child is a United States citizen or not, with some exceptions (Medicaid/SCHIP for the U. S. citizen child, SNAP/"foodstamps" on behalf of a U. S. citizen child, the temporarily expanded child tax credit in 2021–2022, as well as some state and city programs specifically designed to include undocumented residents and their families)

For several years, Pueblo Sin Fronteras, which means "People Without Borders" has organized an annual part protest, part mass migration march, from Honduras, through Mexico, to the United States border, where asylum in the United States is requested. In April 2018, the annual "Stations of the Cross Caravan" saw 1,000 Central Americans trying to reach the United States, prompting President Trump to deem it a threat to national security and announce plans to send the national guard to protect the U. S. border. In October 2018, a second caravan of the year left the city of San Pedro Sula the day after U. S. vice president, Mike Pence, urged the presidents of Honduras, El Salvador and Guatemala to persuade their citizens to stay home.

Over the period 2011–2016, U. S. Border Patrol apprehended 178,825 unaccompanied minors from El Salvador, Honduras, and Guatemala. The provisions of the William Wilberforce Trafficking Victims Protection Reauthorization Act of 2008, which specifies safe repatriation of unaccompanied children (other than those trafficked for sex or forced labor) from countries which do not have a common border with the United States, such as the nations of Central America other than Mexico, made expeditious deportation of the large number of children from Central America who came to the United States in 2014 difficult and expensive, prompting a call by President Barack Obama for an emergency appropriation of $4 billion and resulting in discussions by the Department of Justice and Congress of how to interpret or revise the law in order to expedite handling large numbers of children under the act. A 2016 study found that Deferred Action for Childhood Arrivals (DACA), which allows illegal immigrants who migrated to the United States before their 16th birthday and prior to June 2007 to temporarily stay, did not significantly impact the number of apprehensions of unaccompanied minors from Central America. Rather, the study stated, "the 2008 Williams Wilberforce Trafficking Victims Protection Reauthorization Act, along with violence in the originating countries and economic conditions in both the countries of origin and the United States, emerge as some of the key determinants of the recent surge in unaccompanied minors apprehended along the southwest U. S. Mexico border." A 2017 Center for Global Development study stated that violence was the primary driver behind the surge in unaccompanied Central American minors to the United States: an additional 10 homicides in Central America made 6 unaccompanied children flee to the U. S. The widespread promulgation of false "permiso" rumors by human smugglers, as well as migrant perception of the Obama administration's immigration policies, also played a part in the increase.

In April 2018, then attorney general of the Trump administration Jeff Sessions announced a family separation policy regarding migrants crossing the U. S. southern border without a visa. Migrants and accompanying family members who had entered the country who were alleged to have entered illegally and were apprehended or turned themselves in to Border Control agents were charged with criminal entry. If these family units had children, they were separated, with adults placed in detention centers to await immigration proceedings and the children in separate facilities or with a relative already in the U. S. There was widespread condemnation of this policy including that of notable evangelical Christian leaders such as Franklin Graham.

According to the U. S. Department of Homeland Security, the countries of origin for the largest numbers of illegal immigrants are as follows (as of 2014): The next largest percentages were from Asia (16%), El Salvador (6%), and Guatemala (5%). The Urban Institute also estimates "between 65,000 and 75,000 Canadians currently live illegally in the United States."]] In 2017, illegal border crossing arrests hit a 46 year low, and were down 25% from the previous year. NPR stated that immigrants may be less likely to attempt to enter the U. S. illegally because of President Trump's stance on illegal immigration. The majority of illegal immigrants come from Mexico. Studies have shown that 40 million foreign born residents live in the U. S. 11.7 million of that population is illegal. During the 1950s, there were 45,000 documented immigrants from Central America. In the 1960s, this number more than doubled to 100,000. In the decade after, it increased to 134,000. In 2019, after being threatened with punitive tariffs, Mexico agreed to a deal with the U. S. to better stem the flow of migrants passing through the country to enter the U. S. In September 2019, Mexican foreign minister Marcelo Ebrard stated that immigration to the U. S. through Mexico has decreased significantly, and that this trend is "irreversible. It is something that we think will be permanent."

There are an estimated half million illegal entries into the United States each year. A common means of border crossing is to hire people smugglers to help them across the border. Those operating on the U. S. Mexico border are known informally as coyotajes (coyotes), and are often part of extensive criminal networks throughout Mexico.

A tourist or traveler is considered a "visa overstay" once he or she remains in the United States after the time of admission has expired. The time of admission varies greatly from traveler to traveler depending on the visa class into which they were admitted. According to Pew, between 4 and 5.5 million foreigners entered the United States with a legal visa, accounting for between 33 and 48% of the total unauthorized migrant population. To help track visa overstayers the U. S. VISIT (United States Visitor and Immigrant Status Indicator Technology) program collects and retains biographic, travel, and biometric information, such as photographs and fingerprints, of foreign nationals seeking entry into the United States. It also requires electronic readable passports containing this information. Visa overstayers mostly enter with tourist or business visas.

A smaller number of illegal immigrants entered the United States legally using the Border Crossing Card, a card that authorizes border crossings into the U. S. for a set amount of time. Border Crossing Card entry accounts for the vast majority of all registered non immigrant entry into the United States—148 million out of 179 million total—but there is little hard data as to how much of the illegal immigrant population entered in this way. The Pew Hispanic Center estimates the number at around 250,000–500,000. Most illegal migrants end up being hired by U. S. employers who exploit the low wage market produced through immigration. Typical jobs include: janitorial services, clothing production, and household work. Though PRWORA prevents public benefits from flowing to illegal immigrants, there are exceptions. Illegal immigrants are still entitled to medical assistance, immunizations, disaster relief, and k 12 education. Despite this, federal law still requires local and state governments to deny benefits to those illegal. There were about eight million illegally present workers in the United States in 2010. These workers were 5% of America's workforce. International polls by the Gallup organization from 2013 to 2016 in 156 foreign countries found that about 147 million adults would, if they could, move to the U. S., making it the most desired destination country for potential migrants worldwide, followed by Germany and Canada.

In general, illegal immigrants from Mexico and Central America come to the US as they flee from insecurity and violence in their own country (i. e. forced recruitment in gangs). or in search for better economic opportunities. However, it sometimes also occurs due to political oppression. A study of illegal immigrants from Mexico in the 1978 harvest season in Oregon showed that they earned six times what they could have earned in Mexico, and even after deducting the costs of the seasonal migration and the additional expense of living in the United States, their net U. S. earnings were three times their Mexican alternative. In the 1960s and early 70s, Mexico's high fertility rate caused a large increase in population. While Mexican population growth has slowed, the large numbers of people born in the 1960s and 70s are now of working age looking for jobs. Many workers that took advantage of the program became illegal residents, as they still had incentives to stay in the U. S. despite the fact that they were breaking the law. Although the bracero program had ended, the period still saw a massive spike in migrant population in the U. S.

The United States immigration system provides channels for legal, permanent economic immigration, especially for high skilled workers. For low skilled workers, temporary or seasonal legal immigration is easier to acquire. Outside of this number for permanent immigrants, 480,000 visas are allotted for those under the family preference rules and 140,000 are allocated for employment related preferences. The investigation began when U. S. Border Patrol agents arrested two marines for transporting three illegal Mexican immigrants on July 3, 2019. A few weeks later 16 marines and a U. S. Navy sailor were arrested on base during a battalion formation on July 25, 2019. The last arrest occurred on December 2, 2019, when a marine was caught transporting two illegal Chinese immigrants near the border. The ring leader of the human smuggling operation was identify as Francisco Saul Rojas Hernandez. Some of the marines in court said Francisco Saul Rojas Hernandez would pay them $1,000 per person that they helped transport. 8 marines plead guilty, however some of the marines had their charges dropped after a judge said that the arrest of the 16 marines in front of a battalion formation was a violation of their rights. The U. S. Marine Corps still took administrative or judicial action against the 24 marines involved. According to 1st Lieutenant Cameron Edinburgh, one marine received a general discharge under honorable conditions, at least one marine received a dishonorable discharge, two received bad conduct discharges, and 19 received other than honorable discharges. The Navy sailor was also removed from service with a bad conduct discharge.

Aliens can be classified as unlawfully present for one of three reasons: entering without authorization or inspection, staying beyond the authorized period after legal entry, or violating the terms of legal entry. The maximum prison term is 6 months for the first offense with a misdemeanor and 2 years for any subsequent offense with a felony. In addition to the above criminal fines and penalties, civil fines may also be imposed. Sections 1325(a) and 1326(a), however, do "not apply to an alien whom the Attorney General admits to the United States under section 1157 of this title."

Unlike illegal entry (which is a criminal offense in the United States), it is not a criminal offense for an alien to enter the United States legally and then overstay his or her visa. A visa overstay is a civil violation dealt with through proceedings in immigration court. A person who overstays a visa is subject only to the civil penalties of deportation or removal and restrictions for future applications for another U. S. visa; under provisions of Section 212 of the Immigration and Nationality Act, as amended by 1996 legislation, an alien who "voluntarily departs the United States after being unlawfully present for more than 180 consecutive days but less than 1 year" is subject to a three year bar to readmission to the United States, and an alien who "departs (voluntarily or involuntarily) the United States after being unlawfully present for 1 consecutive year or more" is subject to a ten year bar to readmission to the United States. Since 2007, visa overstays have accounted for a larger share of the growth in the illegal immigrant population than illegal border crossings. Some visa overstays occur unwittingly or inadvertently. In other cases, visa holders enter the United States without the intention to do so, but ultimately decide to do so due to extenuating circumstances, such as dangers in their home countries.

The federal government has primary responsibility for immigration enforcement in the United States. Assistance from state and local police for immigration enforcement has been controversial and legally complicated in various ways. In jurisdictions with majority support for strong immigration enforcement, state and local police often cooperate with federal officials. Some state governments have declared federal enforcement activities insufficient, and attempted to prevent illegal immigration through state law and police. In some jurisdictions where majorities feel federal immigration restrictions are unjust or enforcement actions too harsh, state and local police are prohibited from voluntary cooperation with immigration enforcement agencies. This may include information sharing or acting on ICE detainers. Some jurisdictions prohibit asking about or checking the immigration status of victims, witnesses, or perpetrators, with the goal of encouraging undocumented residents to report crimes without fear of disproportionate consequences or being deported themselves. Many of these have declared themselves sanctuary cities or states. States have considerable power to make legal residency status a requirement for employment and state services including social safety net programs and higher education. The 1982 US Supreme Court decision Plyler v. Doe ruled that K 12 students cannot be denied an education on the basis of immigration status. Whether or not to issue driver's licenses for illegal immigrants became a high profile political issue in the 21st century. In April 2010, Arizona passed SB 1070, at the time the broadest and strictest anti illegal immigration bill in the United States. The Court, however, indicated that future legal challenges to the provision could still be pursued based on, for example, allegations of racial profiling in the use of the clause. The Los Angeles Times reported that the settlement "pulls the last set of teeth from what was once the nation's most fearsome immigration law." A standoff at Eagle Pass began in January 2024 when the governor ordered the Texas National Guard seized control of a park and refused entry to federal border control agents. Abbott and Arizona governor Doug Ducey have arranged for buses to transport migrants released from federal custody to pro sanctuary cities or even the homes of prominent liberal politicians, without coordinating with local officials and sometimes overwhelming local support services. (At times, federal, state, and private facilities along the southern border have also become overwhelmed.) Florida governor Ron DeSantis even once arranged to airlift of migrants to Martha's Vineyard, a wealthy island in liberal Massachusetts.

Illegal immigrants are generally not allowed to receive state or local public benefits, which includes professional licenses. However, in 2013 the California State Legislature passed laws allowing illegal immigrants to obtain professional licenses. On February 1, 2014. Sergio C. Garcia became the first illegal immigrant to be admitted to the State Bar of California since 2008, when applicants were first required to list citizenship status on bar applications.

E Verify is a United States Department of Homeland Security (DHS) website that allows businesses to determine the eligibility of their employees, both U. S. and foreign citizens, to work in the United States. No federal law mandates use of E Verify. Research shows that E Verify harms the labor market outcomes of illegal immigrants and improves the labor market outcomes of Mexican legal immigrants and U. S. born Hispanics, but has no impact on labor market outcomes for non Hispanic Americans. A 2016 study suggests that E Verify reduces the number of illegal immigrants in states that have mandated use of E Verify for all employers, and further notes that the program may deter illegal immigration to the United States in general.

Federal law enforcement agencies, specifically U. S. Immigration and Customs Enforcement (ICE), the United States Border Patrol (U. S. BP), and U. S. Customs and Border Protection (CBP), enforce the Immigration and Nationality Act of 1952 (INA), and to some extent, the United States Armed Forces, state and local law enforcement agencies, and civilians and civilian groups guard the border.

Before 2007, immigration authorities alerted employers of mismatches between reported employees' Social Security cards and the actual names of the card holders. In September 2007, a federal judge halted this practice of alerting employers of card mismatches. The United States government held more than 300,000 people in immigration detention in 2007 while deciding whether to deport them. Deportation proceedings are also referred to as removal proceedings and are typically initiated by the Department of Homeland Security. The United States issues deportations for various reasons which include security, protection of resources, and protection of jobs. Deportations from the United States increased by more than 60 percent from 2003 to 2008, with Mexicans accounting for nearly two thirds of those deported. By the end of 2012, as many people had been deported during the first four years of the Obama presidency as were deported during the eight year presidency of George W. Bush; the number of deportations under Obama totalled 2.5 million by the end of 2015.

Two major pieces of legislation passed in 1996 had a significant effect on illegal immigration and deportations in the United States: the Antiterrorism and Effective Death Penalty Act (AEDPA) and the Illegal Immigration Reform and Immigrant Responsibility Act (IIRIRA). These were introduced following the 1993 World Trade Center bombing and the 1995 Oklahoma City bombing, both of which were terrorist attacks that claimed American lives. These two acts changed the way criminal cases of lawful permanent residents were handled, resulting in increased deportations from the United States. Before the 1996 deportation laws, there were two steps that lawful permanent noncitizen residents who were convicted of crimes went through. The first step determined whether or not the person was deportable. The second step determined if that person should or should not be deported. Before the 1996 deportation laws, the second step prevented many permanent residents from being deported by allowing for their cases to be reviewed in full before issuing deportations. External factors were taken into consideration such as the effect deportation would have on a person's family members and a person's connections with their country of origin. Under this system permanent residents were able to be relieved of deportation if their situation deemed it unnecessary. The 1996 laws however issued many deportations under the first step, without going through the second step, resulting in a great increase in deportations. One significant change that resulted from the new laws was the definition of the term aggravated felony. Being convicted of a crime that is categorized as an aggravated felony results in mandatory detention and deportation. The new definition of aggravated felony includes crimes such as shoplifting, which would be a misdemeanor in many states. The new laws have categorized a much wider range of crimes as aggravated felonies. The effect of this has been a large increase in permanent residents facing mandatory deportation from the United States without the opportunity to plea for relief. The 1996 deportation laws have received a lot of criticism for their curtailing of residents' rights. Under the USA Patriot Act the Attorney General was granted the power to "certify" illegal immigrants that pose a threat to national security. Once an illegal immigrant is certified they must be taken into custody and face mandatory detention which will result in a criminal charge or release. The Patriot Act has been criticized for violating the Fifth Amendment right to due process. Under the Patriot Act, an illegal immigrant is not granted the opportunity for a hearing before given certification.

Complications in deportation efforts ensue when parents are illegal immigrants, but their children are birthright citizens. Federal appellate courts have upheld the refusal by the Immigration and Naturalization Service to stay the deportation of illegal immigrants merely on the grounds that they have U. S. citizen, minor children. Although the DREAM Act has not been enacted by federal legislation, a number of its provisions were implemented by a memorandum issued by Janet Napolitano of the Department of Homeland Security during the Obama administration. To be eligible for Deferred Action for Childhood Arrivals (DACA), one must show that they were under 31 years of age as of 2012; that they came to the United States before their 16th birthday; that they have continuously resided in the United States from June 15, 2007, until the present; that they were physically present in the United States on June 15, 2012, and at the time they applied for DACA; that they were not authorized to be in the United States on June 15, 2012; that they are currently in school, have graduated or obtained a certificate of completion from high school, have obtained a general education development (GED) certificate, or are an honorably discharged veteran of the Coast Guard or Armed Forces of the United States; and that they have not been convicted of a felony, significant misdemeanor, three or more other misdemeanors, and do not otherwise pose a threat to national security or public safety.

There have been two major periods of mass deportations in U. S. history. In the Mexican Repatriation of the 1930s, through mass deportations and forced migration, an estimated 500,000 Mexicans and Mexican Americans were deported or coerced into emigrating, in what Mae Ngai, an immigration historian at the University of Chicago, has described as "a racial removal program". Some illegal immigrants, in some cases along with their U. S. born children (who are citizens according to U. S. law),

A direct effect of the deportation laws of 1996 and the Patriot Act has been a dramatic increase in deportations. Prior to these acts deportations had remained at about an average of 20,000 per year. Between 1990 and 1995 deportations had increased to about an average of 40,000 a year. From 1996 to 2005 the yearly average had increased to over 180,000. In the year 2005 the number of deportations reached 208,521 with less than half being deported under criminal grounds. According to a June 2013 report published by the Washington Office on Latin America, dangerous deportation practices are on the rise and pose a serious threat to the safety of the migrants being deported. These practices include repatriating migrants to border cities with high levels of drug related violence and criminal activity, night deportations (approximately 1 in 5 migrants reports being deported between the hours of 10pm and 5am), and "lateral repatriations", or the practice of moving migrants from the region where they were detained to areas hundreds of miles away. These practices increase the risk of gangs and organized criminal groups preying upon the newly arrived migrants. In 2013, deportation prioritization guidance used by Immigration and Customs enforcement, was extended to Customs and Border Protection, under the Obama Administration's prosecutorial discretion plan. Under the Obama administration, removals peaked in fiscal year (FY) 2012, when 409,849 persons were removed (about 55% of whom had a criminal conviction, with some additional number with a pending criminal charge). and FY 2013, when 438,421 persons were removed. Deportations thereafter declined while still remaining high: there were 414,481 deportations in FY 2014, 235,413 deportations in FY 2015, 240,255 deportations in FY 2016.

In 1995, the United States Congress considered an exemption from the Posse Comitatus Act, which generally prohibits direct participation of U. S. soldiers and airmen (and sailors and marines by policy of the Department of the Navy) in domestic law enforcement activities, such as search, seizure, and arrests. Cities which have been referred to as "sanctuary cities" by various politicians include Washington, D. C.; New York City; Los Angeles; Chicago; San Francisco; Most of these ordinances are in place at the state and county, not city, level. These policies do not prevent the local authorities from investigating crimes committed by illegal immigrants.

Illegal immigrants increase the size of the U. S. economy and contribute to economic growth. A 2016 National Bureau of Economic Research paper found that "legalization would increase the economic contribution of the unauthorized population by about 20%, to 3.6% of private sector GDP." Legalization is also likely to reduce untaxed labor in the informal economy. The study estimated that DACA moved 50,000 to 75,000 unauthorized immigrants into employment. A 2017 study in the Journal of Public Economics found that more intense immigration enforcement increased the likelihood that U. S. born children with illegal immigrant parents would live in poverty.

Illegal immigrants are not eligible for most federally funded safety net programs, and pay more in taxes than similar low income groups because they are not eligible for the federal earned income tax credit. Illegal immigrants are barred from receiving benefits from Medicare, non emergency Medicaid, or the Children's Health Insurance Program (CHIP), and the Medicare program; they also cannot participate in health insurance marketplaces and are not eligible to receive insurance subsidies under the Affordable Care Act. While the aggregate fiscal effects are beneficial to the United States, unauthorized immigration has small but net negative fiscal effects on state and local governments.

Around 2005, an increasing number of banks saw illegal immigrants as an untapped resource for growing their own revenue stream and contended that providing illegal immigrants with mortgages would help revitalize local communities, with many community banks providing home loans for illegal immigrants. At the time, critics complained that this practice would reward and encourage illegal immigration, as well as contribute to an increase in predatory lending practices. One banking consultant said that banks which were planning to offer mortgages to illegal immigrants were counting on the fact that immigration enforcement was very lax, with deportation unlikely for anyone who had not committed a crime. Multiple studies have found that illegal immigration to the United States did not increase violent crime. A 2016 study found no link between illegal immigrant populations and violent crime, although there is a small but significant association between illegal immigrants and drug related crime. A 2017 study found that "Increased undocumented immigration was significantly associated with reductions in drug arrests, drug overdose deaths, and DUI arrests, net of other factors." A 2017 study found that California's extension of driving licenses to unauthorized immigrants "did not increase the total number of accidents or the occurrence of fatal accidents, but it did reduce the likelihood of hit and run accidents, thereby improving traffic safety and reducing costs for California drivers providing unauthorized immigrants with access to driver's licenses can create positive externalities for the communities in which they live." A 2018 study in the American Economic Journal: Economic Policy found that by restricting the employment opportunities for unauthorized immigrants, the Immigration Reform and Control Act of 1986 (IRCA) likely caused an increase in crime. A 2018 PLOS One study estimated that the illegal immigrant population in the United States was 22 million (approximately twice as large as the estimate derived from U. S. Census Bureau figures); an author of the study notes that this has implications for the relationship between illegal immigration and crime suggesting the correlation is lower than previously estimated: "You have the same number of crimes but now spread over twice as many people as was believed before, which right away means that the crime rate among illegal immigrants is essentially half whatever was previously believed." A 2019 analysis found no evidence that illegal immigration increased crime. A 2020 study found little evidence of a relationship between unauthorized immigration and terrorism.

Research suggests immigration enforcement deters unauthorized immigration Immigration enforcement is costly and may divert resources from other forms of law enforcement. Tough border enforcement may also encourage unauthorized immigrants to settle in the United States, rather than regularly travel across the border where they may be captured. Immigration enforcement programs have been shown to lower employment and wages among illegal immigrants, while increasing their participation in the informal economy. A 2015 study found that the 1986 Immigration Reform and Control Act, which legalized almost 3 million immigrants, led to "decreases in crime of 3–5 percent, primarily due to decline in property crimes, equivalent to 120,000–180,000 fewer violent and property crimes committed each year due to legalization". A 2017 review study of the existing literature noted that the existing studies had found that sanctuary cities—which adopt policies designed to avoid prosecuting people solely for being an illegal immigrant—either have no impact on crime or that they lower the crime rate. A second 2017 study in the journal Urban Affairs Review found that sanctuary policy itself has no statistically meaningful effect on crime. The findings of the study were misinterpreted by Attorney General Jeff Sessions in a July 2017 speech when he claimed that the study showed that sanctuary cities were more prone to crime than cities without sanctuary policies. A third study in the journal Justice Quarterly found evidence that the adoption of sanctuary policies reduced the robbery rate but had no impact on the homicide rate except in cities with larger Mexican illegal immigrant populations which had lower rates of homicide. Two studies have found that local cooperation with ICE adversely affect public safety by reducing local reporting of crime by Latino communities. According to a study by Tom K. Wong, associate professor of political science at the University of California, San Diego, published by the Center for American Progress, a progressive think tank: "Crime is statistically significantly lower in sanctuary counties compared to nonsanctuary counties. Moreover, economies are stronger in sanctuary counties—from higher median household income, less poverty, and less reliance on public assistance to higher labor force participation, higher employment to population ratios, and lower unemployment." The study also concluded that sanctuary cities build trust between local law enforcement and the community, which enhances public safety overall. The study evaluated sanctuary and non sanctuary cities while controlling for differences in population, the foreign born percentage of the population, and the percentage of the population that is Latino." After the Obama administration reduced federal immigration enforcement, Democratic counties reduced their immigration enforcement more than Republican counties; a paper by a University of Pennsylvania PhD candidate found "that Democratic counties with higher non citizen population shares saw greater increases in clearance rates, a measure of policing efficiency, with no increase in crime rates. The results indicate that reducing immigration enforcement did not increase crime and rather led to an increase in policing efficiency, either because it allowed police to focus efforts on solving more serious crimes or because it elicited greater cooperation of non citizens with police." According to Cornell University economist Francine Blau and University of California at Berkeley economist Gretchen Donehower, the existing "evidence does not suggest that stepping up enforcement of existing immigration laws would generate savings to existing taxpayers." By complicating circular migration and temporary work by migrants, and by incentivizing migrants to settle permanently in the U. S., the 2017 National Academy of Sciences report on immigration notes that "it is certainly possible that additional costs have been created to the economy by the increased border enforcement, beyond the narrow costs of the programs themselves in the federal budget."

Illegal immigrants sometimes use Social Security numbers belonging to others in order to obtain fake work documentation. In 2009, the U. S. Supreme Court ruled in the case of Flores Figueroa v. United States that illegal immigrants cannot be prosecuted for identity theft if they use "made up" Social Security numbers that they do not know belong to someone else; to be guilty of identity theft with regard to social security numbers, they must know that the social security numbers that they use belong to others.

An estimated 65,000 undocumented youth graduate from high school every year but only 5 to 10 percent go on to college. Research shows that policies regarding tuition and admissions procedures, impact students the most. As of October 2015, twenty states had given undocumented students' in state resident tuition (ISRT) while five states had completely prohibited their enrollment. Without financial aid, students cannot afford higher education, making it difficult for this community to attain social mobility. In 1994, California implemented Proposition 187, prohibiting undocumented students from enrolling in schools and required educators to report students who they suspected were undocumented. Likewise, the state of Alabama in 2011, requiring administrators to report the status of recently enrolled students; which resulted in a 13% dropout rate that year. The National Education Association (NEA) and the National School Board Association (NSBA) in 2009, created guidelines for educators working with undocumented students, informing school personnel about their students' rights concerning immigration legislation as it transpires in the community.

There are significant dangers associated with illegal immigration including potential death when crossing the border. Since the 1994 implementation of an immigration control effort called Operation Gatekeeper, immigrants have attempted to cross the border in more dangerous locations. The foreign ministry in Mexico City has demanded an explanation from San Diego and federal authorities, according to Tijuana newspapers.

A 2017 Science study found that Deferred Action for Childhood Arrivals (DACA), which allows unauthorized immigrants who migrated to the United States as minors to temporarily stay, led to improved mental health outcomes for the children of DACA eligible mothers. A 2017 Lancet Public Health study reported found that DACA eligible individuals had better mental health outcomes as a result of their DACA eligibility. Stringent immigration enforcement has been linked to worse mental health among illegal immigrants. Illegal immigrants, particularly those living in parts of the US with more restrictive policies, are less likely to access health services. If they do see a health care provider, they are less likely to be able to comply with their recommendations. Additionally, illegal immigrants have higher rates of depressive symptoms than legal immigrants. More restrictive policies also negatively impact the likelihood that a pregnant immigrant will receive prenatal care. A quasi experimental study found that after the Postville raid in Iowa in 2008, newborns were 24% more likely to be underweight at birth compared to the year before, adjusting for maternal risk factors and country of origin. Indian, Russian, Thai, Vietnamese and Chinese women have been reportedly brought to the United States under false pretenses. "As many as 50,000 people are illicitly trafficked into the United States annually, according to a 1999 CIA study. Once here, they're forced to work as prostitutes, sweatshop laborers, farmhands, and servants in private homes." U. S. authorities call it "a modern form of slavery". Many Latina women have been lured under false pretenses to illegally come to the United States and are instead forced to work as prostitutes catering to the immigrant population. Non citizen customers without proper documentation that have been detained in prostitution stings are generally deported.

Many Central American migrants are abducted or killed during their journey. A 2015 estimate suggested that as many as 120,000 migrants had disappeared within Mexico during the previous ten years. Thousands are killed or maimed riding the roofs of cargo trains in Mexico.

With deportation as a tool of the U. S. government against illegal immigrants, practices by immigration authorities have drawn the ire of the public and activists—about detention facilities and deportations. In the act of detaining illegal aliens, ICE has come under scrutiny for its practices of separating families. In addition, ICE has been wrongfully assessing ages of unaccompanied children. The Department of Homeland Security rely on dental radiograph tests to ascertain the ages of those in custody. But these tests only determine an age range, often encompassing both minor and adult ages, resulting in many minors being placed in adult prisons. "This American Life" has reported on one wrongfully detained migrant arriving from Cambodia to meet her finance, whose dental tests said she was a minor. She was wrongfully held ICE tests to determine ages of detained migrants have proven at best faulty—and at worst unscientific. Additionally, activists and immigrant advocates have criticized the role of private prison companies in dealing with the detention of illegal immigrants. Reports have detailed people in ICE custody being forced to work for nothing or a dollar a day cooking, doing laundry, and other essential tasks for these prisons. In late December 2017, the U. S. Civil Rights Commission called on Congress and the Department of Homeland Security to investigate abusive labor practices of these private prisons, including other reports saying detainees had been paid less than a dollar a day in the facilities "Voluntary Work Program." In the report, the Commission specifically cited private prisons as a main concern, given the financial benefit of low paid labor being used to "maximize profits."

Celebrities who perform their normal paid duties may suddenly find themselves working illegally if they travel to the United States.

A number of films and at least one novel tell stories based on the infamous voyage of the Golden Venture, a ship carrying would be illegal immigrants from China that ran aground in New York Harbor in 1993.

The 1996 film Deadly Voyage treats the perils endured by would be immigrants attempting to enter the United States illegally.

How Democracy Works Now: Twelve Stories is a 12 part documentary film series that examines the American political system through the lens of immigration reform from 2001 to 2007, from filmmaking team Shari Robertson and Michael Camerini. Several films in the series contain a large focus on the issue of illegal immigration in the U. S. and feature advocates from both sides of the debate. Since the debut of the first five films, the series has become an important resource for advocates, policymakers and educators.

Kamphoefner, Walter D. "What's New About the New Immigration? A Historian's Perspective over Two Centuries." Studia Migracyjne Przegląd Polonijny 45.3 (173) (2019). online