Автомагистраль 491: Путь сквозь каньоны и земли древних цивилизаций.

U. S. Highway in New Mexico, Colorado, and Utah in the United States
Shiprock is where the US 491 crosses the San Juan River and is briefly concurrent with US 64. After passing Shiprock, the route continues north to the Colorado state line. The New Mexico portion has been designated the "John Pinto Highway" by the New Mexico state legislature. It is on the Trails of the Ancients Byway, one of the designated New Mexico Scenic Byways.

The New Mexico Colorado state line is where the highway passes from the Navajo Nation to Ute Mountain Ute tribal lands. The highway passes to the east of the tribe's namesake, Ute Mountain, believed to belong to a great warrior god of the Ute People. US 491 proceeds diagonally to the northwest in the extreme southwestern corner of the state. The highway exits tribal lands near Cortez and Mesa Verde National Park. After leaving Cortez, the road gradually rises in elevation while proceeding towards Utah. Here, the route features large pinto bean farming regions including Dove Creek, which bills itself as the "pinto bean capital of the world". Canyons of the Ancients National Monument is located along the ascent, just west of the highway. Along this ascent is an access road for Hovenweep National Monument at the state line. A portion of the road in Colorado has been designated the Trail of the Ancients, a National Scenic Byway, which uses US 491 as an access for these parks and monuments in southwest Colorado.

Once in Utah, US 491 gradually ascends to the Abajo Mountains. Still visible are large farming regions. Upon reaching an elevation of 7000 feet (2134 m), the highway arrives at a weigh station and reaches the town of Monticello. US 491 enters the town on Central Street and terminates near the city park at an intersection with US 191, which runs along Main Street. All highways in Utah are codified into law; US 491 is defined at Utah Code Annotated §72 4 137(11).

Before the Mexican–American War, when this area was ceded to the United States, the main trade route through this part of Mexico was the Old Spanish Trail. This trail extended from Santa Fe, New Mexico to Los Angeles. The trail had multiple routes; however, the main route proceeded north towards Moab, Utah, one of the few places where the Colorado River can be crossed without having to traverse steep cliffs. The modern US 491 roughly correlates with the main route of the Old Spanish Trail between Cortez, Colorado and its northern terminus. Before 1926, all of modern US 491 existed as state routes. In New Mexico, US 666 absorbed a portion of State Road 32 (NM 32) from Gallup to Shiprock, and completely replaced NM 121 from Shiprock to the Colorado state line. The portion in Colorado was numbered State Highway 106 (SH 106) from the New Mexico state line to Cortez, and SH 10 from Cortez to Utah. At the time, SH 10 traversed the southern portion of Colorado. While most of this corridor today has a U. S. Highway designation, a portion of SH 10 still exists. In Utah, the route was originally numbered State Route 9 (SR 9), which also included what is now US 191 from Monticello to Crescent Junction. Utah has since re used the SR 9 designation for a different road.

The route was upgraded to a U. S. Highway in 1926, as U. S. Route 666. This number was appropriate and in accordance with the road numbering guidelines for U. S. Highways, being the sixth spur along the highway's parent highway, the famed cross continental highway U. S. Route 66, from which US 491 breaks around Gallup, New Mexico. This number was assigned by the American Association of State Highway Officials (AASHO), a coordinating body that created the U. S. Highway System. Over time the route became known as the "Devil's Highway", a reference to the Number of the Beast. as well as making the signs targets for theft. One unnamed highway patrol officer was quoted in USA Today as stating a drunk driving suspect told him, "Triple 6 is evil. Everyone dies on that highway." only the New Mexico portion is statistically a dangerous highway. During the renumbering debate, the Albuquerque Journal opined that the planned highway improvements would do more to reduce fatalities than the renumbering itself. The highway was used as a plot element in films and television, including Route 666, Natural Born Killers, These pieces are not accurate in portraying the route; for example, one depicts the route in Nevada. It ran concurrent with US 66 for 30 miles (48.3 km) before the turn south. The Arizona portion of the highway is known as the Coronado Trail Scenic Byway, as it approximated the path of the Spanish explorer, Francisco Vásquez de Coronado. This portion is noted for mountainous terrain, with hairpin turns and steep grades, that reaches an altitude of over 9000 feet (2743 m). The curves force a speed limit of in spots. US 666 was extended up part of the old route of US 160 to Monticello, Utah, at an intersection with then US 163 (now US 191). In 1985, the Utah Department of Transportation petitioned to extend US 666 northwest to Richfield, but the proposal was rejected. The proposed extension followed SR 95, SR 24, and SR 119. A concurrency with US 191 would have been routed through Blanding and Monticello to connect to the rest of the route. One of the reasons cited for rejecting the proposal was that portions of SR 24 were not built to standards desired for additions to the U. S. Highway System.

In 1985, the US 66 designation was eliminated, leaving US 666 (and other routes) as "orphans". This fact would be used as a supporting factor in later petitions to renumber the highway. In 1992, the part in Arizona was renumbered as an extension of US 191. This truncated US 666 again at Gallup, New Mexico, now at I 40. Officials in Utah reported that five entire sign assemblies had been cut down with a chainsaw and stolen, while New Mexico officials reported that even signs welded to metal posts, as a theft deterrent, had been stolen. Officials speculated from one scene that someone had intentionally crashed a car into the sign post to break the welds. The dedication of the "new" highway was postponed until July 30, 2003, to coincide with the start of construction projects to improve safety on the highway. At the dedication George Blue Horse, a Navajo medicine man, performed a ceremony to remove the curse from the highway. In the Navajo language he stated, "The road itself never ends. It goes on generation to generation. The new number is a good one. The new road will be a medicine." Construction on the final phase was originally scheduled to begin January 2008,

Note: The Utah mileposts are posted in a west to east direction, while Colorado's and New Mexico's mileposts are posted in a south to north direction.