What Decided the U.S.-Canada Border? The War of 1812 and Subsequent Treaties

The War of 1812 was the pivotal event. The stalemate led to:

• Treaty of Ghent (1814): Restored pre-war borders but left disputes unresolved.
• Rush-Bagot Agreement (1817): Demilitarized the Great Lakes, easing tensions.
• Convention of 1818: Set 49th Parallel from Lake of the Woods to Rockies.
• Webster-Ashburton Treaty (1842): Finalized Maine–New Brunswick border, resolved other disputes.
• Oregon Treaty (1846): Extended 49th Parallel to Pacific.

The war's inconclusive outcome forced negotiated settlements that created today's peaceful border.