The 1783 Treaty of Paris that ended the American Revolutionary War left certain sections of the boundary between the United States and Canada undefined. In the first decades of the 19th century, an expanding population in northern Maine led to competitive friction between rival groups of loggers in Maine and New Brunswick. Eventually, the situation heated into a conflict known as the Aroostook War. While the “war” was bloodless, forces were raised on both sides, making clear a pressing need to define the border.
In 1842, President John Tyler’s secretary of state Daniel Webster met with British Foreign Minister Alexander Baring, the first Baron Ashburton, to resolve this. The treaty that resulted, known as the Webster-Ashburton Treaty, clearly defined the borders between Maine and New Brunswick, as well as the Great Lakes area. Additional matters addressed in the treaty concerned matters of extradition between the two nations and agreement on the part of the United States to strengthen its policing of the illegal slave trade.