Why Is the US–Canada Border a Straight Line?

For more than 2,000 km, the border between the United States and Canada follows a single line of latitude: the 49th parallel. Why did two countries split a continent this way? We follow the line from the Convention of 1818 and the Oregon Treaty of 1846 to the star-sighting surveyors whose markers still define it, and find out why the 'straight' border is really a chain of short straight segments. Along the way: the Northwest Angle in Minnesota and Point Roberts in Washington, two pieces of the US you can't reach over land without passing through Canada; why the eastern border follows rivers and lakes instead; and the 20-foot cleared vista the International Boundary Commission keeps open through the forest. Historical regions shown on the maps (Louisiana Purchase, Rupert's Land, Oregon Country, the disputed Maine lands) are approximate. CHAPTERS 0:00 A Border Drawn With a Ruler 0:33 A Tangle of Rivers 1:07 The 1818 Shortcut 1:45 Oregon and the Vancouver Island Dip 2:21 Why the Line Isn't Straight 3:01 The Northwest Angle 3:49 Point Roberts 4:13 The East Was Never Straight 4:56 The Vista 5:26 The Longest Border on Earth SOURCES (links in the pinned comment) • International Boundary Commission – Boundary Facts • International Boundary Commission – The Boundary • International Boundary Commission – History • International Boundary Commission – FAQ • International Boundary Commission – Section E: Gulf of Georgia to the Northwesternmost Point of Lake of the Woods • International Boundary Commission – Joint Report, Gulf of Georgia to the Northwesternmost Point of Lake of the Woods (Ottawa, 1937) • International Boundary Commission – Treaty of 1925 (English text) • US Department of State, Office of the Historian – FRUS 1925 Vol. I, Doc. 387 • US Department of State – U.S. Relations With Canada • Natural Resources Canada – International Boundaries • Avalon Project, Yale Law School – Convention of 1818 • The Canadian Encyclopedia – Convention of 1818 • The Canadian Encyclopedia – Forty-ninth Parallel • The Canadian Encyclopedia – Rupert's Land • State Historical Society of North Dakota (ND Studies) – The Northern Border • Canadian Geographic Education – The 49th Parallel (CGclassroom) • US Department of State, Office of the Historian – Louisiana Purchase, 1803 • US Department of State, Office of the Historian – The Oregon Territory, 1846 • Avalon Project, Yale Law School – Oregon Treaty, 1846 • National Archives (DocsTeach) – Oregon Treaty • Legislative Assembly of British Columbia – 1846: 49th Parallel Becomes International Boundary • Avalon Project, Yale Law School – Treaty of Paris 1783 • US Department of State, Office of the Historian – Treaty of Paris, 1783 • Minnesota Historical Society (MNopedia) – Minnesota State Boundaries • Minnesota Department of Natural Resources – Itasca State Park summer map • Explore Minnesota (state tourism office) – Northwest Angle • HistoryLink.org – Point Roberts: Thumbnail History • US Department of State, Office of the Historian – Webster-Ashburton Treaty, 1842 Historical regions and physical zones drawn on the map are approximate. Imagery: NASA Earth Observatory Blue Marble; Sentinel-2 cloudless (s2maps.eu) by EOX IT Services GmbH, contains modified Copernicus Sentinel data 2016 (CC BY 4.0). Borders and lakes: Natural Earth. Music: original. New map questions every few days. Subscribe so you don't miss the next one. #Geography #Maps #History #Canada #USA #49thParallel