Canada and the United States have had a long and complex relationship that has had a significant impact on each other's history, economy, and culture.

The two countries have historically considered themselves among the "closest allies". They share the longest border () between any two sovereign states, and are one of the largest bilateral trading partnerships in the world. Americans rank Canada as one of their respective most favoured nations and historically, a majority of Canadians have held mostly favorable views of the United States. Despite both countries continuing to be close security and strategic partners, political and economic relations rapidly deteriorated during President Donald Trump's second term due to the 2025 U.S. trade war with Canada and U.S. annexation threats towards Canada, with 2025 surveys showing increased and unprecedented distrust and negative views of the United States government by Canadians.

Since the end of World War II, the economies and supply chains of both countries had grown to be increasingly integrated. In 2024, every day, around 328,000 people and $3.6 billion (US$2.6 billion) in goods and services crossed the Canada–U.S. border resulting in around $1.3 Trillion annually. The close economic partnership was facilitated by shared economic interests and previously 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 led to harmonised regulations on food and manufactured goods. Despite these facts, increasingly recurring and amplifying disputes have included trade disagreements, environmental concerns, uncertainty over oil exports, illegal immigration, terrorism threats, and illicit drug trafficking. A trade disputes over softwood lumber has existed for decades resulting in one of the largest and most enduring trade disputes between the two nations.

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 refused to participate in U.S. military operations that are not sanctioned by the United Nations, such as the Vietnam War, the 2003 invasion of Iraq and 2026 Iran war. Canadian peacekeeping is a distinguishing feature that Canadians feel sets their military foreign policy apart from the United States.

Canadian anti-Americanism and American anti-Canadianism have manifested themselves in a variety of ways, ranging from political to cultural due to the asymmetric nature of the relationship. Defining themselves as "not Americans" has been a recurring theme in Canadian identity. Starting with the American Revolution, when Loyalists were resettled in Nova Scotia and Quebec (in present day Canada) between 1782-83 a vocal element in Canada has warned against American dominance or annexation. The War of 1812 saw another attempt by the United States to conquer Canada, and invasions across the border in both directions, however, the war ended with unchanged borders. The British stopped aiding Indigenous attacks on the United States, and the United States never again attempted to invade Canada.John Herd Thompson, Canada and the United States: ambivalent allies (2008). As Britain decided to disengage, fears of an American takeover played a role in the Canadian Confederation (1867).

Country comparison Canada United States of America Flag Population 41,651,653 Area Population Density Capital Ottawa Washington, D.C. Largest City Toronto – 2,794,356 (6,202,225 Metro) New York City – 8,600,710 (19,006,798 Metro) Government Federal parliamentary constitutional monarchy Federal presidential constitutional republic First Leader Victoria (Monarch)John A. Macdonald (Prime Minister) George Washington Current Leaders Charles III (Monarch)Mark Carney (Prime Minister) Donald Trump Official languages English and French English GDP (PPP) US$2.723 trillion $65,500 per capita US$30.616 trillion $89,599 per capita

History

Colonial wars

Before the British conquest of French Canada in 1760, there had been a series of wars between the British and the French that were fought out in the colonies as well as in Europe and on the high seas. In general, the British heavily relied on American colonial militia units, while the French heavily relied on their First Nation allies. The Iroquois Nation were important British allies. Much of the fighting involved ambushes and small-scale warfare in the villages along the border between New England and Quebec. The New England colonies had a much larger population than Quebec, so major invasions came from south to north. The tension along the border was exacerbated by religion, as the French Catholics and English Protestants had a deep mutual distrust.Howard H. Peckham, The Colonial Wars (1965) There was a naval dimension as well, involving privateers attacking enemy merchant ships.

England seized Quebec from 1629 to 1632, and Acadia in 1613 and again from 1654 to 1670; These territories were returned to France by the peace treaties. The major wars were (to use American names), King William's War (1689–1697); Queen Anne's War (1702–1713); King George's War (1744–1748), and from 1755 to 1763 the French and Indian War (known in Europe as the Seven Years’ War).

New England soldiers and sailors were critical to the successful British campaign to capture the French fortress of Louisbourg in 1745, and (after it had been returned by treaty) to capture it again in 1758.

American Revolutionary War

At the outset of the American Revolutionary War, the American revolutionaries hoped the French Canadians in Quebec and the Colonists in Nova Scotia would join their rebellion. They were pre-approved for joining the United States in the Articles of Confederation. When northeastern Quebec was invaded, thousands joined the American cause and formed regiments that fought during the war; however, most remained neutral, and some joined the British effort. Britain advised the French Canadians that the British Empire already enshrined their rights in the Quebec Act, which the American colonies had viewed as one of the Intolerable Acts. The American invasion was a fiasco, and Britain tightened its grip on its northern possessions; in 1777, a major British invasion of New York led to the surrender of the entire British army at Saratoga, and led France to enter the war as an ally of the U.S. The French Canadians largely ignored France's appeals for solidarity.Mason Wade, The French Canadians, 1760–1945 (1955) p. 74.

The American forces had much better success in southwestern Quebec, owing to the leadership of Virginia militia leader George Rogers Clark. In 1778, 200 men under Clark, supplied and supported mainly by Virginia, came down the Ohio River near Louisville, Kentucky, marched across southern Illinois, and then captured Kaskaskia without loss of life. From there, part of his men took Vincennes, but was soon lost to British Lieutenant Colonel Henry Hamilton, the commander at Fort Detroit. Clark later retook it in the Siege of Fort Vincennes in February 1779. Roughly half of Clark's militia in the theater were Canadian volunteers sympathetic to the American cause.

In the end, America won its independence, and the Treaty of Paris compelled Britain to cede parts of southwestern Canada to them. Following America's independence, Canada became a refuge for about an estimated 70,000 or 15% of Loyalists who either wanted to leave the U.S. or were compelled by Patriot reprisals to do so. Among the original Loyalists, there were 3,500 free African Americans. Most went to Nova Scotia, and in 1792, 1,200 migrated to Sierra Leone. About 2,000 black slaves were brought in by Loyalist owners; they remained slaves in Canada until the Empire abolished slavery in 1833. Around 85% of the loyalists remained in the new United States and became American citizens.Thomas B. Allen, Tories: Fighting for the King in America's First Civil War (2011) p. xviii

War of 1812 (1812–1815)

The Treaty of Paris of 1783, which ended the American Revolutionary War, called for British forces to vacate all their forts south of the Great Lakes border. Britain refused to do so, citing the failure of the newly independent United States to provide financial restitution for Loyalists who had lost property in the war. The Jay Treaty in 1795 with Great Britain resolved that lingering issue, and the British departed the forts. Thomas Jefferson saw the nearby British presence as a threat to the United States, and so he opposed the Jay Treaty, and which became one of the major political issues in the United States at the time.Bradford Perkins, The First Rapprochement: England and the United States, 1795–1805 (1955) Thousands of Americans immigrated to Upper Canada (Ontario) from 1785 to 1812 to obtain cheaper land and better tax rates prevalent in that province; despite expectations that they would be loyal to the U.S. if a war broke out, in the event they were largely non-political.

Tensions mounted again after 1805, erupting into the War of 1812 (1812–1815), when the United States Congress, approved/signed by the fourth President James Madison (1751–1836, served 1809–1817), declared war in June 1812 on Britain. The Americans were angered by British harassment of U.S. ships on the high seas and seizure of 6,000 sailors from American ships, severe restrictions against neutral American trade with France, and British support for hostile Native American tribes in Ohio and territories the U.S. had gained in 1783. American "honor" was an implicit issue. While the Americans could not hope to defeat the Royal Navy and control the seas, they could call on an army much larger than the British garrison in Canada, and so a land invasion of Canada was proposed as the most advantageous means of attacking the British Empire. Americans on the western frontier also hoped an invasion would bring an end to British support of Native American resistance to American expansion, typified by Tecumseh's coalition of tribes.Alan Taylor, The Civil War of 1812: American Citizens, British Subjects, Irish Rebels, & Indian Allies (2010). Americans may also have wanted to acquire Canada.George F. G. Stanley, War of 1812: The Land Operations (1983), p. 32David Heidler, Jeanne T. Heidler, The War of 1812 (2004), p. 4