The Webster–Ashburton Treaty, signed August 9, 1842, was a treaty that resolved several border issues between the United States and the British North American colonies. Signed under John Tyler's presidency, it resolved the so-called Aroostook War. The provisions of the treaty included:The settlement of the location of the Maine–New Brunswick border, which was the primary cause of the Aroostook War. Establishment of the border between Lake Superior and the Lake of the Woods, originally defined in the Treaty of Paris in 1783; Reaffirmation of the location of the border in the westward frontier up to the Rocky Mountains defined in the Treaty of 1818; Definition of seven crimes subject to extradition; Agreement that the two parties would share use of the Great Lakes; Agreement that there should be a final end to the slave trade on the high seas.

The Collins–Valentine line, or Valentine–Collins line, is the boundary at approximately 45 degrees north latitude that separates the province of Quebec from the states of New York and Vermont. It was surveyed and marked by survey monuments in 1771–3 by John Collins, surveyor-general of Quebec, and Thomas Valentine, a commissioner appointed by the government of New York.