Movements for the annexation of Canada to the United States

Various individuals and movements within Canada and the United States have campaigned in favour of U.S. annexation of parts of or all of Canada or have predicted it without endorsing it since their common origin as parts of British America.

Before the United States even declared its independence, there were efforts to have parts of what is now Canada join the Thirteen Colonies in their complaints against Great Britain. Invasions were attempted during the American Revolution and the War of 1812. One last diplomatic effort was made in the wake of the American Civil War (during which some British support was given to the Confederacy) and Canadian Confederation, but the 1871 Treaty of Washington did not include any such provisions.

Various groups and individuals in what is now Canada have campaigned for part or all of Canada (earlier, British North America) to join the United States, generally over unhappiness with British rule or the Canadian federal government. After a spike of interest, they have faded into obscurity, often after their concerns were addressed within the existing system.

Historian Joseph Levitt is quoted in a 1993 book as saying:

Since the Treaty of Washington in 1871, when it first de facto recognized the new Dominion of Canada, the United States has never suggested or promoted an annexationist movement in Canada. No serious force has appeared on the American political scene that aimed to persuade or coerce Canadians into joining the United States. And no serious initiative for any move in this direction has come from the Canadian side either.

Surveys have suggested that a minority of Canadians would potentially support annexation, ranging from as many as 20 percent in a survey by Léger Marketing in 2001 to as few as seven percent in another survey by the same company in 2004. One poll in the 2020s, noted by the Toronto Star, showed that about 50% of Americans are against Canada joining, 25% are in favour, and 25% are not sure.

After winning a second term as president in the 2024 election, U.S. president Donald Trump has said he wants Canada to be annexed as the 51st state of the United States. Canadians responded strongly against these calls, with Prime Minister Justin Trudeau saying, "There isn't a snowball's chance in hell that Canada would become a part of the United States".