Canada–United States relations

Canada's long and complex relationship with the United States has had a significant impact on its history, economy, and culture. The two countries consider themselves among the "closest [of] allies". They share the longest border (8,891 km (5,525 mi)) between any two nations in the world, and also have significant military interoperability. Both Americans and Canadians have generally ranked each other as one of their respective "favorite nations". Canadian peacekeeping is deeply embedded in Canadian culture and a distinguishing feature that Canadians feel sets their foreign policy apart from the United States. Canadian Anti-Americanism manifests itself in a variety of ways, ranging from political, to cultural.

Starting with the American Revolution, when Loyalists were resettled in Canada, a vocal element in Canada has warned against American dominance or annexation. The War of 1812 saw invasions across the border in both directions, but the war ended with unchanged borders. The British ceased aiding Native American attacks on the United States, and the United States never again attempted to invade Canada. Apart from minor unsuccessful raids, it has remained peaceful. As Britain decided to disengage, fears of an American takeover played a role in the Canadian Confederation (1867), and Canada's rejection of free trade (1911). Military collaboration was close during World War II and continued throughout the Cold War, bilaterally through NORAD and multilaterally through NATO. A high volume of trade and migration continues between the two nations, as well as a heavy overlapping of popular and elite culture; a dynamic that has generated closer ties, especially after the signing of the Canada–United States Free Trade Agreement in 1988 and the North American Free Trade Agreement in 1994.

Recent difficulties have included repeated trade disputes, environmental concerns, Canadian concern for the future of oil exports, the issue of illegal immigration and the threat of terrorism. Trade has continued to expand, especially following the 1988 FTA, the 1994 North American Free Trade Agreement (NAFTA), and the 2020 United States–Mexico–Canada Agreement (USMCA), which has progressively merged the two economies. Co-operation on many fronts, such as the ease of the flow of goods, services, and people across borders are to be even more extended, as well as the establishment of joint border inspection agencies, relocation of U.S. food inspectors agents to Canadian plants and vice versa, greater sharing of intelligence, and harmonizing regulations on everything from food to manufactured goods, thus further increasing the American-Canadian assemblage.