U.S.-Canada relations: A timeline

This history of the relationship between the United States and Canada is perhaps best told in the story of the border. The United States dates to 1776 and Canada (as a self-governing country) to 1867, but the two countries didn’t get around to officially demarcating the border between them until 1908.

Why did it take so long? Well, because with the exception of a few War of 1812 border skirmishes, there really wasn’t much need to codify it. The two countries’ relations were cordial and cooperative, with the U.S. having opened its first diplomatic office in Nova Scotia in 1833. As U.S. Pres. John F. Kennedy said in a speech to Canada’s Parliament in 1961:

Geography has made us neighbors. History has made us friends. Economics has made us partners. And necessity has made us allies. Those whom nature hath so joined together, let no man put asunder.

But by 2025, U.S. Pres. Donald Trump had called into question just about everything regarding the relationship—including the physical border, the world’s longest. To understand more about the sometimes collegial, sometimes frosty, sometimes stunningly kind and courageous relationship between the two countries, read on.

1854: The first trade agreement

Even before there was a sovereign border, there was trading between the countries and agreements (and disagreements) on tariffs. The first such agreement was the Elgin-Marcy Reciprocity Agreement, which allowed each party to import and export abundant natural resources and agricultural products, including timber, grain, meats, and cheeses, and afforded the U.S. some fishing rights. Though the treaty was initially popular, Canada (known at the time as British North America) soured on it as fear of U.S. incursion and takeover of provinces became more prevalent. Then lingering resentment over Britain’s support of the South in the American Civil War ultimately led to the U.S. withdrawing from the treaty in 1866.

1911: An election over a trade treaty

The U.S. Congress approved a new tariff agreement that reduced tariffs on food products and eliminated all tariffs on agricultural goods. But in Canada there was suspicion that the deal would benefit the U.S. more than Canada, and the nagging fears of a U.S. takeover crept into the political campaign. In the end the Conservatives, who opposed the treaty, defeated the Liberal Party of Wilfrid Laurier, whose government had negotiated the pact.

1930: The Great Depression and more tariff woes

With the U.S. economy in the throes of the Great Depression, Pres. Herbert Hoover signed the Smoot-Hawley Tariff Act, which raised tariffs on a range of agricultural and industrial foreign imports and led a number of countries, including Canada, to follow suit. Canada also sought better trade deals with European allies, further intensifying the global economic crisis. Pres. Franklin D. Roosevelt negotiated reductions in tariffs with Canada in 1935.

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1938–41: A common defense

With the world on the brink of war in the late 1930s, the relationship between the U.S. and Canada expanded to include military and defense topics. In August 1938, speaking at Queen’s University at Kingston, in Ontario, Pres. Franklin D. Roosevelt made clear the American position when he said: “I give to you assurance that the people of the United States will not stand idly by if domination of Canadian soil is threatened by any other empire.” That declaration paved the way for the 1940 Ogdensburg Agreement, which was reached in a meeting involving Roosevelt and Canadian Prime Minister W.L. Mackenzie King. The agreement created the Permanent Joint Board on Defense, which included representatives from both countries and encouraged frank discussions on issues of mutual national security. The Hyde Park Declaration, which would come in 1941 and was signed by King and Roosevelt, cemented the economic relationship between the two countries, and production of war-related materials ramped up.

1949: Creation of NATO

In the aftermath of the Second World War and with the Cold War intensifying, the United States, Canada, and 10 European allies formed the North Atlantic Treaty Organization (NATO) to help secure western Europe. The creation of NATO included the now-famous Article 5 language, which states that “an armed attack against one or more of them in Europe or North America shall be considered an attack against them all.” Some of the NATO operations Canadian forces have served in:

• 1995–2004: Provided support in the wake of the breakup of the former Yugoslavia and subsequent combat missions over Kosovo
• 2003–11: Deployed some 40,000 members of the Canadian military to provide peacekeeping aid and combat forces in Afghanistan
• 2004–11 and 2018: Contributed to the training of Iraqi security forces

1958: NORAD

The military relationship between the two countries deepened with the 1958 adoption of the North American Air Defense Command (NORAD), tasked with providing surveillance and defense of the airspace over the continent. After the September 11 terror attacks, the bilateral agreement was expanded to offer additional security amid heightened security concerns and later to cover maritime issues as well.

1965: The Auto Pact

By the mid-1960s, the relationship between the United States and Canada had pivoted somewhat to economic issues. The agreement signed by U.S. Pres. Lyndon B. Johnson and Canadian Prime Minister Lester B. Pearson eliminated tariffs on most auto parts traded between the countries and provided a boon to the Canadian auto industry. It also served to lower the price of American-made cars, opening the Canadian market to U.S. auto manufacturers.

1971: The Nixon shock

Faced with a foundering economy marked by high unemployment and inflation largely the result of the war in Vietnam, in August 1971 Pres. Richard Nixon addressed the American people, saying, “The time has come for a new economic policy for the United States. Its targets are unemployment, inflation, and international speculation.” The plan involved, among other measures, cuts to federal spending and the imposition of 10 percent tariffs on all imported goods. Canada was not exempted from the tariffs, and Nixon even threatened to cancel the Auto Pact. Nixon ultimately backed down after striking a deal on monetary policy. But when he visited Canada the next year, he outlined to Parliament his view of U.S.-Canada relations:

Our policy toward Canada reflects the new approach we are taking in all of our foreign relations—an approach which has been called the Nixon Doctrine. That doctrine rests on the premise that mature partners must have autonomous, independent policies: Each nation must define the nature of its own interests; each nation must decide the requirements of its own security; each nation must determine the path of its own progress.

1980: The Canadian Caper

In January 1980 the Canadian government and the U.S. Central Intelligence Agency teamed up to get six American diplomats—who had evaded capture as part of the 1979 Iranian takeover of the U.S. embassy—out of Iran. The two governments came up with a plan to forge passports for the six, concocting a cover story that they were members of a film crew scouting locations for a possible Hollywood film. The daring escape provided a rare bit of good news related to the hostage crisis, and in the United States banners reading “Thank You, Canada” were widely seen. The full details of the plan, including the CIA’s role in it, were not made public until 1997. In 2012 Ben Affleck directed and starred in Argo, a film based on the events that led to the release of the diplomats. It won the Academy Award for best picture.

1989–94: Continental free trade movement

Signed by Canadian Prime Minister Brian Mulroney and U.S. Pres. Ronald Reagan, the Canada-U.S. Free Trade Agreement aimed to eliminate all trade barriers between the two countries. It was followed by the 1994 implementation of the controversial NAFTA (North American Free Trade Agreement), which included the United States, Canada, and Mexico and superseded the earlier deal. Many of those opposed to the plans expressed concern about the U.S. having an outsize role in the treaties and therefore leveraging the deals to its advantage. The reality was that the agreement wound up being neither as good as its proponents promised nor as dire as its detractors feared. NAFTA would stay in effect until 2020.

September 2001: Come from away

Within hours of the tragedy unfolding on September 11, 2001, Canada proved itself a good neighbor. With U.S. airspace closed, more than 200 planes made unscheduled landings at Canadian airports. Gander, Newfoundland, population 10,000, almost doubled in size when some three dozen planes carrying 6,700 passengers suddenly descended. The village rose to the challenge: School buses lined up to transport passengers off the planes, and residents opened their homes, offering meals, showers, and hospitality to the strangers, who were colloquially referred to as the “come-from-aways.” The phrase would inspire the title of a 2013 musical that told the story.

2015: Keystone XL Pipeline dispute

In a largely symbolic gesture, U.S. Pres. Barack Obama refused to allow TransCanada to build an almost 1,200-mile (1,931-km) oil pipeline extension from Canada to the Gulf Coast of the United States. The pipeline issue, which had been under review for seven years, had taken on an outsize role in the ongoing debate over climate change and greenhouse gases. Canadian Prime Minister Stephen Harper had made the pipeline something of a referendum on U.S.-Canada relations. But his successor, Justin Trudeau, was more sanguine about the issue, acknowledging his disappointment with the rejection while adding: “The Canada-U.S. relationship is much bigger than any one project.”

2020: U.S.–Mexico–Canada Agreement

In 2018 Trump imposed tariffs of 10 to 25 percent on Canadian aluminum and steel coming into the United States. That prompted a tit-for-tat retaliation from Canada, but nonetheless Trump, Trudeau, and Mexican Pres. Enrique Peña Nieto signed a three-way trade deal that same year. The U.S.–Mexico–Canada Agreement (USMCA) would go into effect in 2020 and aimed to provide new regulations on digital technology, tighten regulation on auto manufacturing, and impose new labor standards. The USMCA replaced NAFTA, which Trump had widely disparaged. It required the three members to meet six years after its implementation to decide if they would renew the deal for 16 years. In July 2026 Trump declined to do so.

2025–26: Annexation and more tariffs

The second Trump administration marked a significant negative shift in U.S.-Canada relations. On February 1, 2025, Trump signed an executive order imposing 25 percent tariffs on Canada (and Mexico), citing the influx of fentanyl and illegal immigration. (Trudeau dismissed the fentanyl justification for the tariffs as “completely bogus.”) Canada responded by imposing tariffs on U.S. goods ranging from coffee to automobile parts. During February calls between Trump and Trudeau, Trump called into question the 1908 treaty establishing the border between the two countries. Then in March, Trump posted on Truth Social that the solution to the trade dispute was “for Canada to become our cherished Fifty First State.”

In January 2025 Trudeau’s Liberal government collapsed and new elections were called. The assumption had been that the election was the Conservative Party’s to win, but in the weeks before the April vote, anti-Trump backlash was so profound that Liberal Mark Carney, in a stunning upset, was elected prime minister. Carney, who had campaigned hard on the wave of Canadian nationalism, declared in his election-night speech:

America is not Canada. And Canada never, ever, will be part of America in any way, shape, or form. We didn’t ask for this fight, but Canadians are always ready when someone else drops the gloves.

The normally polite Canadians did not take what they saw as an assault on their sovereignty quietly. They took to the streets in protest, staged boycotts of American goods, canceled travel to the United States, and even booed “The Star-Spangled Banner” at major sporting events.

Tensions continued to escalate in 2026. Carney—without naming Trump or the United States—gave a stinging speech at the World Economic Forum in Davos, Switzerland, in which he said of the current world situation: “We are in the midst of a rupture, not a transition.” The next months would be marked by Trump’s attempt to stop the opening of the Gordie Howe International Bridge connecting Detroit and Windsor, Ontario (it ultimately opened in July), and Trump’s renaming of Lake Ontario to Lake America in August. Also in August, Trump imposed 50 percent tariffs on some Canadian goods, and Carney vowed to match the sanctions “dollar for dollar.” The $1 billion in new tariffs on products ranging from dairy to motorcycles that went into effect at the end of September was almost immaterial in a trade relationship that totaled $880 billion. Their real impact was in the global message they delivered.

Also in September, the European Union took the unprecedented step of offering Canada “associate member” status, an indication that not just Canada was rethinking its long-standing relationship with the United States. Speaking to the European Parliament in France, with Carney at her side, European Commission President Ursula von der Leyen said: “We must urgently reimagine our partnerships.”