[108] In 1817, the United States and Britain signed the Rush–Bagot Treaty, which regulated naval armaments on the Great Lakes and Lake Champlain and demilitarized the border between the U.S. and British North America.[109] The Treaty of 1818, also with Great Britain, was concluded October 20, 1818, and fixed the present Canada–United States border from Minnesota to the Rocky Mountains at the 49th parallel. The accords also established a joint U.S.–British occupation of Oregon Country for the next ten years.[110] Though they did not solve every outstanding issue between the U.S. and Britain, the treaties allowed for greater trade between the United States and the British Empire and helped avoid an expensive naval arms race in the Great Lakes.[108] Late in Monroe's second term, the U.S. concluded the Russo-American Treaty of 1824 with the Russian Empire, setting the southern limit of Russian sovereignty on the Pacific coast of North America at the 54°40′ parallel (the present southern tip of the Alaska Panhandle).[111]

Acquisition of Florida
Main articles: Adams–Onís Treaty and Seminole Wars
Map showing the results of the Adams–Onís Treaty of 1819
Spain had long rejected repeated American efforts to purchase Florida. 