Cádiz and Marbella |- | style="background:#b0e0e6;" | ! scope="row" style="background:#b0e0e6;" | Mediterranean Sea | style="background:#b0e0e6;" | |} See also Territorial evolution of the United States The 49th parallel north – another important parallel of latitude in American history, since it became the boundary between the United States and Canada from northern Minnesota all the way west to the Pacific Ocean at Puget Sound. This boundary was established in two separate treaties with the British Empire, the first one in 1818. The Parallel 54°40′ north – another important parallel of latitude in American history. References n36°30′ Borders of Arkansas Borders of Tennessee Borders of Kentucky Borders of Missouri Borders of Oklahoma Borders of Texas Geographic history of the United States