Canada–United States relations

Canada and the United States have a long and complex relationship that has had a significant impact on Canada's history, economy, and culture. The two countries have long considered themselves among the "closest 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 historically ranked each other as one of their respective "favorite nations".

Since the end of World War II, the economies and supply chains of both countries have grown to be fully integrated. In 2024 every day, around 400,000 people and $2.7 billion in goods and services cross the Canada–U.S. border. The close economic partnership has been facilitated by shared values and strong bilateral trade agreements. The North American Free Trade Agreement (NAFTA) and its successor, the United States–Mexico–Canada Agreement (USMCA), have played a pivotal role in fostering economic cooperation and integration between the two nations. Cross-border projects, such as communications, highways, bridges, and pipelines have led to shared energy networks and transportation systems. The countries have established joint inspection agencies, share data and have harmonized regulations on everything from food to manufactured goods. Despite these facts, disputes have included repeated trade disagreements, environmental concerns, Canadian concern for the future of oil exports, the issue of illegal immigration, the threat of terrorism and illicit drug trade.

Military collaboration was close during World War II and continued throughout the Cold War, bilaterally through NORAD and multilaterally through NATO. However, Canada has long been reluctant to participate in U.S. military operations that are not sanctioned by the United Nations, such as the Vietnam War or the 2003 invasion of Iraq. Canadian peacekeeping is a distinguishing feature that Canadians feel sets their military foreign policy apart from the United States.

Canadian anti-Americanism has manifested itself in a variety of ways, ranging from political, to cultural. Not being an "American" is a popular theme of Canadian identity. 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. As Britain decided to disengage, fears of an American takeover played a role in the Canadian Confederation (1867). A trade war involving the United States, Canada, and Mexico began on February 1, 2025, when U.S. president Donald Trump signed orders imposing near-universal tariffs on goods from the two countries entering the United States. The two countries' relations saw rapid deterioration during Trump's second term due to his tariffs and annexation threats towards Canada, with recent polls suggesting increased distrust of the United States by Canadians.