Сен-Жон өзені: АҚШ-Қанада шекарасы және мәдени мұрасы

River defining parts of the border of Maine and New Brunswick

The Saint John River (; Maliseet Passamaquoddy: Wolastoq) is a river flowing within the Dawnland region from headwaters in the Notre Dame Mountains near the Maine Quebec border through western New Brunswick to the northwest shore of the Bay of Fundy. Eastern Canada's longest river, its drainage basin is one of the largest on the east coast at about This “River of the Good Wave” and its tributary drainage basin formed the territorial countries of the Wolastoqiyik and Passamaquoddy First Nations (named Wolastokuk and Peskotomuhkatik, respectively) prior to European colonization, and it remains a cultural centre of the Wabanaki Confederacy to this day. The Webster–Ashburton Treaty following the Aroostook War established a border between New Brunswick and Maine following 130 km (80 miles) of the river, while a tributary forms 55 km (35 miles) of the border between Quebec and Maine. Maine communities along the river include Fort Kent, Madawaska, and Van Buren. New Brunswick settlements through which it passes include, moving downstream, Edmundston, Fredericton, Oromocto, and Saint John. It is regulated by hydro power dams at Mactaquac, Beechwood, and Grand Falls, New Brunswick.

Samuel de Champlain visited the mouth of the river on the feast day of John the Baptist in 1604 and renamed it the Rivière Saint Jean or Saint John River in English. Many waterways in the system retain their original pre European names. The Maliseet call it the Wolastoq, meaning bountiful and good and seek to restore this name.

The headwaters are in the New England/Acadian forests of Maine and Quebec, including the Southwest, Northwest, and Baker branches, and the Allagash River flowing into New Brunswick at Edmundston where it is joined by the Madawaska River.

The middle section runs from the confluence of the Aroostook and Tobique rivers, flowing southeast to Mactaquac Dam. Other tributaries in this section include the Meduxnekeag River. This area is the only place in Atlantic Canada where Appalachian Hardwood Forest is found. Plants rare for the province include wild ginger, black raspberry, wild coffee, maidenhair fern, showy orchis and others. This forest type, also known as the Saint John River Valley Hardwood Forest, once spread of much of the area and has been reduced to less than one percent of the land area because of human activities. This is an area of rolling hills and soils that are the most fertile and heavily farmed in New Brunswick. Soils are fine, loamy, and well drained glacial tills overlaying limestone and sandstone. with a sill, or rise in depth near the mouth of a fjord caused by a terminal moraine. From the Grand Bay (New Brunswick), the waterway becomes narrower and deeper forming a gorge where at the Reversing Falls incoming tide forces the flow of water to reverse against the prevailing current. A wedge of salt water, below a surface covering of fresh water, extends upriver to the 10 metre (30') shallows at Oak Point beyond which it cannot advance. In early spring, upper sections of the river can experience ice jams causing flooding. In the lower sections in the broader floodplain, flooding may occur during late spring from the volume of water which must make its way through the narrow gorge at the Reversing Falls. Legally, all of the river downstream of a point between Fredericton and Mactaquac Provincial Park is considered tidal. The river is mostly calm, except for waterfalls at Grand Falls and at the Beechwood Dam. Floods have been documented for more than 300 years. Flooding has occurred in Edmundston, Grand Falls, Perth Andover, Hartland, Woodstock, and most severely around Fredericton and Saint John. Major flooding occurred in 1923, with water 8 metres (26') above normal winter low. In 1936, high temperatures quickened snowmelt, and heavy rain raised the water level to 8.9 metres (30'), about 7.6 metres (25') above summer level. Similar circumstances led to the same level of high water in the 1973 flood. Similar major flooding occurred again in 2018 and 2019. Since 2019, flooding has not been as severe. The severity and frequency of flooding is expected to increase, with climate change. It is predicted that New Brunswick's average temperature will increase by 5 C (9°F) by the year 2100, and that precipitation will increase.

At the end of the last glacial period, following the retreat of the Laurentide Ice Sheet about 13,000 years ago, the area was stripped bare of vegetation and soil. By about 10,000 years ago, Paleo Indians probably occupied what is now New Brunswick. Although the basin has been subject to human influence for thousands of years, the Native American impact was minimal partly because of their small numbers, and partly because they practiced low intensity agriculture. Major disturbances did not begin until the early 1800s The Passamaquoddy hunted sea mammals along the northwest shore of the Bay of Fundy while speaking a mutually intelligible dialect with the Wolastoqiyik who were inland hunters along the upper Saint John River and its tributaries. The Wolastoqiyik dealt with freshets by having their village above the floodplain, for example Meductic, The Wolastoqiyik identified themselves as inhabitants of the river their canoes traveled for hunting, fishing, and trading. After spending the winter hunting and trapping in the interior, the villages of Ouigoudi at the mouth of the river and Aukpaque at the head of navigation were summer gathering places accessible to European fur traders. Rivalry between English and French fur traders pre dated colonization of North America. Colonization pressure was less severe along the Saint John River where the cold water eddy of the Gulf of Maine kept the growing season shorter than Massachusetts and the Nova Scotia peninsula nearer the warm Gulf Stream. The earliest Acadians were descendants of the French sailors and shipwrights whose focus on fishing, trading, and boat repair rather than agriculture minimized land use conflicts. These Acadians maintained favorable relationships with the First Nations while King Philip's War encouraged the Wolastoqiyik to join the Wabanaki Confederacy in military action against New England. French colonists populated the lower river valley as part of Acadia, with Fort Nashwaak in present day Fredericton, Fort Boishebert at the confluence of the Saint John and Nerepsis rivers. In the French seigneurial system lands were arranged in long, narrow strips, called seigneuries, along the banks of the river. However this was not practical given the seasonal flooding, and the Acadians moved to higher ground. As the longest river between the Chesapeake Bay and the Gulf of Saint Lawrence, the Saint John offered one of the best transportation corridors for First Nations refugees to retreat from the English colonization of North America's Atlantic coast. About a thousand Wolastoqiyik sheltered a hundred Acadian families retreating up the Saint John to avoid the Acadian Expulsion as the St. John River Campaign killed livestock and burned Acadian settlements as far upstream as Sainte Anne des Pays Bas.

While the upstream Wolastoqiyik and their Acadian allies rejected both Canada and United States sovereignty after English victories in the French and Indian War, many Loyalist refugees from the American Revolutionary War resettled in Saint John at the mouth of the river and in Sainte Anne des Pays Bas which was renamed Fredericton. Persistent hostilities with the Wolastoqiyik had prevented the English treaty signatories from mapping the river headwaters. Aside from ambiguity as to which tributary might be considered the source of the Saint Croix River, the Saint John River does not flow directly south as might have been assumed from knowledge of the better mapped Hudson and Connecticut Rivers. Of greater concern to Canada, however, was discovery of how close the drainage divide was to the south bank of the Saint Lawrence, leaving Canada with a narrow band of unfavorable terrain for construction of a road to connect Atlantic Canada to Quebec through the winter months when ice closed the Saint Lawrence. Canada chose to interpret the treaty's intention as keeping the entire Saint John drainage basin under Canadian control. Surviving Acadian and Wolastoqiyik refugees continued to resist British rule while moving upriver to the Acadian Landing Site west of the Saint Croix treaty boundary where they were joined by other Acadian refugees who had fled to Quebec. Large numbers of people began settling the area in the early 1800s, mostly Scottish and Irish, and by the end of the 1850s much of the central Saint John valley had been cleared of old growth forest for farming. Before the advent of railways, the river was an important trade route, including timber rafting. After the state of Maine obtained independence from Massachusetts in 1820, Maine lumbermen encouraged Acadian refugees to form the independent Republic of Madawaska, and began diverting the Saint John headwaters into the Penobscot River so log driving could float timber harvested in the upper Saint John watershed to Bangor sawmills. These provocations encouraged clarification of the disputed Canada–United States border boundary by the Webster–Ashburton Treaty of 1842 which allocated the north bank of the Saint John west of the Saint Croix to Canada in exchange for some territory further west.

Today's Trans Canada Highway follows the route of the proposed English road along the north bank of the river through the disputed portion of the drainage. Most of the Saint John drainage on the disputed south bank became Aroostook County, Maine, where the town of Madawaska still shares the Acadian French dialect with Edmundston across the river. Historic isolation has helped preserve the dialect. The Allagash River and Baker Branch of the Saint John River upstream of Madawaska flow through the sparsely populated Maine North Woods. These black spruce forests were a primary source of pulpwood for Maine paper mills through the 20th century. Distance from Maine cities encouraged landowners to employ Quebec lumberjacks. Édouard Lacroix developed innovative transportation methods for the river headwaters including a road from Lac Frontière, Quebec to build the isolated Eagle Lake and West Branch Railroad in 1927 and the Nine Mile Bridge over the river in 1931. The lower river has been developed for agriculture and industry. Francophone Quebecers moved into the northern river valley. In the interwar period, many older farms were abandoned due to urbanization, and allowed to reforest. In 2011, the entire watershed was designated the Wolastoq National Historic Site, and is as the traditional territory of the Wolastoqiyik First Nation.