Canada–United States border facts for kids
The Canada–United States border, officially known as the International Boundary, is the longest international border in the world shared between the same pair of countries. The terrestrial boundary (including small portions of maritime boundaries on the Atlantic, Pacific, and Arctic coasts, as well as the Great Lakes) is 8,891 kilometres (5,525 mi) long, including 2,475 kilometres (1,538 mi) shared with Alaska. It is Canada's only land border.
The Treaty of Paris of 1783 ended the American Revolutionary War between Great Britain and the United States. In the second article of the Treaty, the parties agreed on all boundaries of the United States, including, but not limited to, the boundary to the north along then-British North America. The agreed-upon boundary included the line from the northwest angle of Nova Scotia to the northwesternmost head of the Connecticut River and proceeded down along the middle of the river to the 45th parallel of north latitude.
The parallel had been established in the 1760s as the boundary between the provinces of Quebec and New York (including what would later become the State of Vermont). It was surveyed and marked by John Collins and Thomas Valentine from 1771 to 1773.
The St. Lawrence River and the Great Lakes became the boundary further west, between the United States and what is now Ontario. Northwest of Lake Superior, the boundary followed rivers to the Lake of the Woods. From the northwesternmost point of the Lake of the Woods, the boundary was agreed to go straight west until it met the Mississippi River. In fact, that line never meets the river since the river's source is further south.
Jay Treaty (1794)
The Jay Treaty of 1794 (effective 1796) created the International Boundary Commission, which was charged with surveying and mapping the boundary. It also provided for the removal of British military and administration from Detroit, as well as other frontier outposts on the U.S. side. The Jay Treaty was superseded by the Treaty of Ghent (effective 1815) concluding the War of 1812, which included pre-war boundaries.
Signed in December 1814, the Treaty of Ghent ended the War of 1812, returning the boundaries of British North America and the United States to the state they were prior to the war. In the following decades, the United States and the United Kingdom concluded several treaties that settled the major boundary disputes between the two, enabling the border to be demilitarized. The Rush–Bagot Treaty of 1817 provided a plan for demilitarizing the two combatant sides in the War of 1812 and also laid out preliminary principles for drawing a border between British North America and the United States.
London Convention (1818)
The Treaty of 1818 saw expansion of both British North America and the US, where the boundary extended westward along the 49th parallel, from the Northwest Angle at Lake of the Woods to the Rocky Mountains. The treaty extinguished British claims to the south of that line up to the Red River Valley, which was part of Rupert's Land. The treaty also extinguished U.S. claims to land north of that line in the watershed of the Missouri River, which was part of the Louisiana Purchase. This amounted to three small areas, consisting of the northern part of the drainages of the Milk River (today in southern Alberta and southwestern Saskatchewan), the Poplar River (Saskatchewan), and Big Muddy Creek (Saskatchewan). Along the 49th parallel, the border vista is theoretically straight, but in practice follows the 19th-century surveyed border markers and varies by several hundred feet in spots.
Webster–Ashburton Treaty (1842)
Disputes over the interpretation of the border treaties and mistakes in surveying required additional negotiations, which resulted in the Webster–Ashburton Treaty of 1842. The treaty resolved the Aroostook War, a dispute over the boundary between Maine, New Brunswick, and the Province of Canada. The treaty redefined the border between New Hampshire, Vermont, and New York on the one hand, and the Province of Canada on the other, resolving the Indian Stream dispute and the Fort Blunder dilemma at the outlet to Lake Champlain.
The part of the 45th parallel that separates Quebec from the U.S. states of Vermont and New York had first been surveyed from 1771 to 1773 after it had been declared the boundary between New York (including what later became Vermont) and Quebec. It was surveyed again after the War of 1812. The U.S. federal government began to construct fortifications just south of the border at Rouses Point, New York, on Lake Champlain. After a significant portion of the construction was completed, measurements revealed that at that point, the actual 45th parallel was three-quarters of a mile (1.2 km) south of the surveyed line. The fort, which became known as "Fort Blunder", was in Canada, which created a dilemma for the U.S. that was not resolved until a provision of the treaty left the border on the meandering line as surveyed. The border along the Boundary Waters in present-day Ontario and Minnesota between Lake Superior and the Northwest Angle was also redefined.
Oregon Treaty (1846)
An 1844 boundary dispute during the Presidency of James K. Polk led to a call for the northern boundary of the U.S. west of the Rockies to be 54°40′N related to the southern boundary of Russia's Alaska Territory. However, Great Britain wanted a border that followed the Columbia River to the Pacific Ocean. The dispute was resolved in the Oregon Treaty of 1846, which established the 49th parallel as the boundary through the Rockies.
Boundary surveys (mid–19th century)
The Northwest Boundary Survey (1857–1861) laid out the land boundary. However, the water boundary was not settled for some time. After the Pig War in 1859, arbitration in 1872 established the border between the Gulf Islands and the San Juan Islands.
The International Boundary Survey (or, the "Northern Boundary Survey" in the US) began in 1872. Its mandate was to establish the border as agreed to in the Treaty of 1818. Archibald Campbell led the way for the United States, while Donald Cameron, supported by chief astronomer Samuel Anderson, headed the British team. This survey focused on the border from the Lake of the Woods to the summit of the Rocky Mountains.
In 1903, following a dispute that arose because of the Klondike Gold Rush, a joint United Kingdom–Canada–U.S. tribunal established the boundary of southeast Alaska.
On April 11, 1908, the United Kingdom and the United States agreed, under Article IV of the Treaty of 1908 "concerning the boundary between the United States and the Dominion of Canada from the Atlantic Ocean to the Pacific Ocean", to survey and delimit the boundary between Canada and the U.S. through the St. Lawrence River and Great Lakes, in accordance with modern surveying techniques, and thus accomplished several changes to the border. In 1925, the International Boundary Commission's temporary mission became permanent for maintaining the survey and mapping of the border; maintaining boundary monuments and buoys; and keeping the border clear of brush and vegetation for 6 m (20 ft). This "border vista" extends for 3 m (9.8 ft) on each side of the line.
In 1909, under the Boundary Waters Treaty, the International Joint Commission was established for Canada and the U.S. to investigate and approve projects that affect the waters and waterways along the border.
As a result of the 2001 September 11 attacks, the Canada–U.S. border was shut without any warning, and no goods or people were allowed to cross. In the wake of the impromptu border closure, procedures were jointly developed to ensure that commercial traffic could cross the border even if people were restricted from crossing. These procedures were later used for a border closure caused by the COVID-19 pandemic in 2020.
In response to the COVID-19 pandemic in Canada and the United States, the governments of Canada and the United States agreed to close the border to "non-essential" travel on March 21, 2020, for an initial period of 30 days. The closure has been extended 15 times since then; it expired on July 21, 2021. However, in mid-June 2021, the Canadian government announced it will ease some entry requirements for fully vaccinated Canadian nationals, permanent residents, and foreign nationals starting on July 5, 2021. In mid-July, the Canadian government announced that fully vaccinated American citizens and permanent residents can visit Canada starting August 9, 2021. The American government reopened its land border to fully vaccinated Canadian citizens effective November 8, 2021. Provided that COVID cases remain stable and/or decline, fully vaccinated international visitors can enter Canada starting September 7. The 2020–21 closure was reportedly the first blanket, long-term closure of the border since the War of 1812.
Essential travel, as defined by Canadian and US regulations, includes travel for employment or education purposes. "Non-essential" travel to Canada, includes travel "for an optional or discretionary purpose, such as tourism, recreation or entertainment." The U.S. Department of Homeland Security issued defined non-essential travel to include "tourism purposes (e.g., sightseeing, recreation, gambling, or attending cultural events)" and gave an extensive, non-exhaustive definition of what sorts of travel qualify as essential.
Business advocacy groups, noting the substantial economic impact of the closure on both sides of the border, called for more nuanced restrictions in place of the blanket ban on non-essential travel. The Northern Border Caucus, a group in the US Congress composed of members from border communities, made similar suggestions to the governments of both countries. Beyond the closure itself, US President Donald Trump also initially suggested the idea of deploying United States military personnel near the border with Canada in connection with the pandemic. He later abandoned the idea following vocal opposition from Canadian officials.
- In Spanish: Frontera entre Canadá y Estados Unidos
- United States Customs and Border Protection
- Canada–United States relations
- Indian barrier state, British plans to set up a new country in the Old Northwest
- John Lewis Tiarks, a British surveyor of the border
- Joseph Smith Harris' account of the Northwest Boundary Survey
- Mexico–United States border
Images for kids
U.S. counties (or county equivalents) sharing a land or water border with Canada Land border Water border only
Canada Border Services Agency and U.S. Customs and Border Protection agents reviewing identification. Valid identification is required for crossing the border.
A United States Border Patrol agent tracking someone in harsh winter conditions on the northern border
Members of the Royal Canadian Mounted Police waiting for migrants to cross at Roxham Road in August 2017
The Horseshoe Falls and the Niagara River marks the Ontario-New York border. Lakes and waterways make up most of Ontario's borders with the United States.
Entrance to a U.S. pre-clearance area at Vancouver International Airport. Pre-clearance areas are situated in several Canadian airports to help expedite the customs process.
Ambassador Bridge is a suspension bridge that connects Detroit, Michigan, with Windsor, Ontario. The bridge is North America's busiest international crossing in terms of trade volume, carrying more than one quarter of all merchandise trade between Canada and the US.
A ferry departing Wolfe Island, Ontario for Cape Vincent, New York
The Haskell Library sits on the international boundary, with the boundary marked by a black line on the floor of its reading room
Campobello Island is a practical exclave of Canada, with land access to the mainland being only to Maine
Map of Alaska and the Beaufort Sea. The cross-hatched region marks the disputed maritime boundary between Canada and the U.S.