Canada and the United States share the longest border in the world. But despite the (mostly) peaceful relations that currently define their relationship, that border was composed through violence, fierce disagreement, and competition.\nEditor's Choice: A Montrealer Won The Lottery TWICE In The Same Day & Both Are Lifelong Prizes\nSome regions, however, ended up in the United States by sheer accident.\nBelow are six areas that were either supposed to remain Canadian territory or were at one time claimed by Canadian and British authorities.\nTL;DR: We'll look at six areas that were either once claimed by the British/Canadians or were given to the United States accidentally.\nThere is already a movement to reclaim at least one of these places. Maybe one day Canada can retake them all.\nVia Google Maps\nNorthwest Angle\nA recent petition to the White House urges the U.S. government to consider ceding the Northwest Angle to Canada, where it would likely become part of Manitoba.\nThe Lake of the Woods separates this little notch of land from mainland Minnesota, of which it is a part, and is sometimes only accessible through Canada.\nAccording to the CBC, this border anomaly was entirely accidental. The treaty that ended the American Revolutionary War and set boundaries between the new United States and British Canada stipulates that the U.S. border would extend west from the northwesternmost point of the Lake of the Woods to the Mississippi River.\nBut the river actually commences well south of the lake. The consequence of this error in colonial maps is this annoying little bite into what should be Canadian territory.\nIf this petition gains traction, however, the Northwest Angle might eventually become part of the True North.\nVia Google Maps\nNorthern Maine\nThe Treaty of Paris set unclear divisions between British Canada and the United States in northern New England.\nWhile our southernly neighbours claimed territory almost as far north as the Saint Lawrence River, the British argued that about half of the land that is now Maine belonged to them.\nThe map above gives a (very) rough approximation of that land. But from the 18th-century map below, we can more accurately determine the extent of the British claim. If they had their way, Canada would stretch to about the River Clyde (near the top of the map).\nIt would take a few skirmishes, the Seven Years' War, and the intervention of the King of the Netherlands as neutral arbiter to settle the dispute and give Maine the shape it has today.\nVia Norman B. Leventhal Map & Education Center at the Boston Public Library\nVia Google Maps\nPoint Roberts\nPoint Roberts is another consequence of haphazard boundaries and map-making. According to the National Post, negotiators set the then-westernmost boundary between Canada and the U.S. at the 49th parallel unaware that a small peninsula actually lied south of that line across the Strait of Georgia.\nThe result is Point Roberts, Washington, which is just south of Vancouver. Residents must travel through Canada to reach the mainland U.S.\nVia Norman B. Leventhal Map & Education Center at the Boston Public Library\nWashington state\nIt wasn't until the mid-nineteenth century that the British and Americans settled the dispute over territory on the western coast of the continent. While the U.S. claimed most of what is now British Columbia (see map above), the Brits in Canada asserted control of what is now Washington state.\nVia Google Maps\nSouthern Alaska\nThe southern tail of Alaska denies Canada a much longer Pacific Coast. In the 19th century, it also prevented the True North from establishing a sea route to its gold veins to the east.\nCanada claimed all but a sliver of the "Alaska panhandle" until an agreement in 1903 settled the current boundary.\nVia Google Maps\nNorthern New Hampshire\nVague treaty language and poor cartography also led to this dispute. The Connecticut River was meant to form the boundary between Quebec and the United States in New Hampshire. But disagreement about which stream of water composed the beginning of the river produced competing claims.\nResidents of this northwestern area of New Hampshire were taxed by both powers and declared themselves an independent country out of frustration. Eventually, the Brits just gave up their claim to the land.\nCanada could have been even larger if it had retained these areas — imagine that!