Two hundred and fifty years ago, just a few months after the first shots of the American Revolution rang out in Massachusetts, the colonies’ fledgling Continental Army set its sights to the north. In August 1775, some 1,200 soldiers marched into British-controlled Canada with an ambitious plan: to seize the province of Quebec.

The local population was mostly French, and the British had controlled Quebec for only 12 years. It seemed reasonable to many Americans that the people there would be eager to join the fight to throw off British rule. In fact, a year earlier, the Continental Congress had formally invited Quebec to join the American rebellion and become the 14th colony.

“We come with professed intention of eradicating tyranny, and of giving liberty, and security to this oppressed Province,” General Richard Montgomery, who commanded part of the invading force, wrote in a letter to Quebec’s inhabitants.

But the people of Quebec, who were largely Catholic, remained suspicious of the mostly Protestant Americans. They didn’t flock to the American cause.

The American dream of conquering Quebec ended on December 31, 1775, when some 1,100 Americans tried and failed to capture the walled city in the middle of a blinding snowstorm.

Despite those early tensions—and current ones involving trade and border issues—the relationship between Canada and what would become the United States has evolved into a close and mutually beneficial one over the centuries. The two nations share the longest land border in the world. And for most of our history, both Americans and Canadians have crossed back and forth over the 5,525-mile boundary without much fuss. There are even homes, businesses, and public buildings, including a library, with rooms on both sides of the divide.

“These countries developed one of the most effective transnational relationships on the face of the earth,” says Jon Parmenter, a Cornell University historian of colonial North America. “That relationship relied on an extensive amount of trust between these two nations.”

A few months after the American Revolution started in Massachusetts, the colonies’ new Continental Army set its sights to the north. In August 1775, some 1,200 soldiers marched into British-controlled Canada with an ambitious plan. They wanted to seize the province of Quebec.

The British had controlled Quebec for only 12 years, and the local population was mostly French. It seemed reasonable to many Americans that the people there would be eager to join the fight to overthrow British rule. In fact, a year earlier, the Continental Congress had formally invited Quebec to join the American rebellion and become the 14th colony.

“We come with professed intention of eradicating tyranny, and of giving liberty, and security to this oppressed Province,” General Richard Montgomery, who commanded part of the invading force, wrote in a letter to Quebec’s inhabitants.

But the people of Quebec were mostly Catholic. They remained suspicious of the mostly Protestant Americans. They didn’t flock to the American cause.

The American dream of conquering Quebec ended on December 31, 1775. During a blinding snowstorm, some 1,100 Americans tried and failed to capture the walled city.

Despite those early tensions—and current ones involving trade and border issues—the relationship between Canada and the United States has evolved into a close and mutually beneficial one over the centuries. The two nations share the longest land border in the world. And for most of our history, both Americans and Canadians have crossed back and forth over the 5,525-mile boundary without much fuss. There are even homes, businesses, and public buildings, including a library, with rooms on both sides of the divide.

“These countries developed one of the most effective transnational relationships on the face of the earth,” says Jon Parmenter, a Cornell University historian of colonial North America. “That relationship relied on an extensive amount of trust between these two nations.”

But as the Revolutionary War-era invasion of Quebec demonstrates, the long history of U.S.-Canadian partnership has been punctuated by episodes of tension. During and after the American Revolution, many colonists who remained loyal to Great Britain fled north to the safety of Canada, which remained a British colony until 1867.

During the War of 1812 between the U.S. and Britain, several battles broke out along the U.S.-Canadian border. In 1813, American forces captured and burned the British-held fort of York in Ontario—a settlement now known as Toronto, Canada’s largest city. But the fort had little strategic value, so American troops left after setting the fires, sailing back across Lake Ontario to the U.S.

When it comes to trade, the two nations have often cooperated and sometimes sparred. In 1890, President William McKinley attempted to use high tariffs—taxes on imported goods—to pressure Canada to join the U.S. Instead, Canada shifted to relying more heavily on trade with Britain. In 1911, the U.S. Congress approved an agreement providing free trade of agricultural and other food products between Canada and the U.S. But the treaty fell apart later that year after the election of a new Canadian government that believed allowing free trade would lead to American control of Canada.

In 1930, as the Great Depression began to take hold, the U.S. implemented wide-ranging tariffs intended to support American farmers and industries. The so-called Smoot-Hawley tariffs, aimed at many countries including Canada, prompted anger among Canadians—and a backlash. Canada imposed additional tariffs on American goods and once again pivoted toward British imports.

“Every time the Americans jacked up their tariffs, we would tend to trade more with the British,” explains Robert Bothwell, an emeritus professor of Canadian history at the University of Toronto.

Nevertheless, politically, the two nations have forged a close partnership. In the modern era, Canada has been one of America’s key military allies; it fought alongside the U.S. in both world wars, the Korean War (1950-53), and the Gulf War (1990-91).

Since 1958, the U.S. and Canada have jointly operated the North American Aerospace Defense Command, or NORAD, which is responsible for protecting the entire North American continent against an air attack. During the Cold War (1946-91), the U.S. put significant military resources into defending Canadian territory in the Arctic against a possible invasion by the Soviet Union.

But like the Revolutionary War-era invasion of Quebec, there have been episodes of tension between the U.S. and Canada. During and after the American Revolution, many colonists who remained loyal to Great Britain went to Canada, which remained a British colony until 1867.

During the War of 1812 between the U.S. and Britain, several battles broke out along the U.S.-Canadian border. In 1813, American forces captured and burned the British-held fort of York in Ontario. Today the settlement is known as Toronto, Canada’s largest city. But the fort had little strategic value, so American troops left after setting the fires. They sailed back across Lake Ontario to the U.S.

When it comes to trade, the two nations have often cooperated and sometimes fought. In 1890, President William McKinley attempted to use high tariffs—taxes on imported goods—to pressure Canada to join the U.S. Instead, Canada shifted to relying more heavily on trade with Britain. In 1911, the U.S. Congress approved an agreement providing free trade of agricultural and other food products between Canada and the U.S. But the treaty fell apart later that year after the election of a new Canadian government. They feared that allowing free trade would lead to American control of Canada.

In 1930, as the Great Depression began to take hold, the U.S. implemented wide-ranging tariffs intended to support American farmers and industries. The so-called Smoot-Hawley tariffs were aimed at many countries including Canada. The tariffs prompted anger among Canadians and a backlash. Canada imposed additional tariffs on American goods and once again went back to British imports.

“Every time the Americans jacked up their tariffs, we would tend to trade more with the British,” explains Robert Bothwell, an emeritus professor of Canadian history at the University of Toronto.

Nevertheless, politically, the two nations have formed a close partnership. Canada has been one of America’s key military allies. It fought alongside the U.S. in both world wars, the Korean War (1950-53), and the Gulf War (1990-91).

Since 1958, the U.S. and Canada have jointly operated the North American Aerospace Defense Command, or NORAD. It is responsible for protecting the entire North American continent against an air attack. During the Cold War (1946-91), the U.S. put significant military resources into defending Canadian territory in the Arctic against a possible invasion by the Soviet Union.

In 1961, President John F. Kennedy summed up the modern relationship between the two nations in an address to the Canadian Parliament: “Geography has made us neighbors, history has made us friends, economics has made us partners, and necessity has made us allies.”

Over the years, Canada has remained a dependable ally. During the 1979 Iran hostage crisis, when Iranian revolutionaries attacked the U.S. Embassy in Tehran and took 66 Americans hostage, it was the Canadian government that helped six American diplomats escape, by allowing them to pose as houseguests in the home of the Canadian ambassador and supplying them with Canadian passports.   

Following the terrorist attacks on September 11, 2001, the U.S. government abruptly shut down American airspace, stranding hundreds of planes that were on their way to American destinations. Canada immediately found places for the planes to land, welcoming more than 30,000 stranded Americans in a moment of crisis. At the same time, Canadian firefighters and emergency medical workers rushed to New York City to assist in the rescue and recovery efforts.

In 1961, President John F. Kennedy summed up the modern relationship between the two nations in an address to the Canadian Parliament: “Geography has made us neighbors, history has made us friends, economics has made us partners, and necessity has made us allies.”

Over the years, Canada has remained a dependable ally. During the 1979 Iran hostage crisis, Iranian revolutionaries attacked the U.S. Embassy in Tehran. They took 66 Americans hostage.  The Canadian government helped six American diplomats escape by allowing them to pose as houseguests in the home of the Canadian ambassador and supplying them with Canadian passports.

Following the terrorist attacks on September 11, 2001, the U.S. government abruptly shut down American airspace. Hundreds of planes were stranded on their way to American destinations. Canada immediately found places for the planes to land and welcomed more than 30,000 displaced Americans in a moment of crisis. At the same time, Canadian firefighters and emergency medical workers rushed to New York City to assist in the rescue and recovery efforts.

Still, there have been moments of political disagreement. In the 1960s, Canada didn’t support the Vietnam War. Tens of thousands of young Americans who opposed the conflict fled to Canada to avoid being drafted. And in 1965, Canadian Prime Minister Lester Pearson gave a speech in Philadelphia in which he called for the U.S. to stop bombing Vietnam. The fact that Pearson criticized American policy while on U.S. soil enraged President Lyndon B. Johnson, who lifted Pearson by his shirt collar and yelled at him during a private meeting the following day.

Today the two nations remain deeply intertwined. At least 70 energy pipelines cross the border. U.S. and Canadian phone systems are so integrated that it’s hard to tell you’re making an international call between the two. More than 1 million Americans live in Canada. In 2024, Canada was the top source of international visits to the U.S., with more than 20 million Canadians crossing their Southern border. Both nations claim similar values including freedom, justice, and equality, and have long shared much of their pop culture.

“These two countries are, and always have been, remarkably similar,” says Bothwell, the professor of Canadian history.

Still, there have been moments of political disagreement. Canada didn’t support the Vietnam War. In the 1960s, tens of thousands of young Americans fled to Canada to avoid being drafted. And in 1965, Canadian Prime Minister Lester Pearson gave a speech in Philadelphia in which he called for the U.S. to stop bombing Vietnam. The fact that Pearson criticized American policy while on U.S. soil angered President Lyndon B. Johnson. He lifted Pearson by his shirt collar and yelled at him during a private meeting the following day.

Today the two nations remain deeply linked. At least 70 energy pipelines cross the border. U.S. and Canadian phone systems are so integrated that it’s hard to tell you’re making an international call between the two. More than 1 million Americans live in Canada. In 2024, Canada was the top source of international visits to the U.S. More than 20 million Canadians crossed their Southern border. Both nations claim similar values including freedom, justice, and equality, and have long shared much of their pop culture.

“These two countries are, and always have been, remarkably similar,” says Bothwell, the professor of Canadian history.

For decades, a free trade agreement helped make Canada America’s largest trading partner and vice versa. However, President Donald Trump, citing what he says has been an uneven playing field, has taken an aggressive stance with Canada. Trump imposed 35 percent tariffs on most goods imported from Canada as well as a 10 percent tariff on Canadian electricity and a 50 percent tax on steel and aluminum.

Trump says these tariffs are necessary to bolster U.S. industries and jobs, and that Canada’s trade policies in certain industries are unfair to American businesses.

“Canada has been ripping us off for years on lumber and dairy products,” Trump said in March, explaining the tariffs.

For decades, a free trade agreement helped make Canada America’s largest trading partner and vice versa. However, President Donald Trump, citing what he says has been an uneven playing field, has taken an aggressive position with Canada. Trump imposed 35 percent tariffs on most goods imported from Canada. Other changes include a 10 percent tariff on Canadian electricity and a 50 percent tax on steel and aluminum.

Trump says these tariffs are necessary to bolster U.S. industries and jobs. He also claims that Canada’s trade policies in certain industries are unfair to American businesses.

“Canada has been ripping us off for years on lumber and dairy products,” Trump said in March, explaining the tariffs.

The tariffs, Trump argues, are also meant to pressure Canada to secure its border with the U.S. against illegal drugs and migrants. In addition, Trump has repeatedly raised the idea of eliminating the border entirely by having Canada become the 51st American state—an idea that large majorities of Canadians have rejected in recent polls.

“What the Canadian people clearly have stated, virtually without exception, is: This will never, ever happen,” Prime Minister Mark Carney said in May.

In protest of Trump’s policies, many Canadians have boycotted American goods or canceled trips to the U.S. Andrew Holman, a Canada expert at Bridgewater State University in Massachusetts, is distressed by the current state of relations between these two longtime allies. But he’s hopeful that the long history of friendship will ultimately prevail.

“Despite these minor flare-ups that happen from time to time, a good way to think about the U.S.-Canadian relationship,” he says, “is that the ability to reconcile the relationship has always outweighed any impulse toward conflict.”

The tariffs, Trump argues, are also meant to pressure Canada to secure its border with the U.S. against illegal drugs and migrants. In addition, Trump has repeatedly raised the idea of eliminating the border entirely by having Canada become the 51st American state. Large majorities of Canadians have rejected this idea in recent polls.

“What the Canadian people clearly have stated, virtually without exception, is: This will never, ever happen,” Prime Minister Mark Carney said in May.

In protest of Trump’s policies, many Canadians have boycotted American goods or canceled trips to the U.S.

Andrew Holman, a Canada expert at Bridgewater State University in Massachusetts, is upset by the current state of relations between these two longtime allies. But he’s hopeful that the long history of friendship will ultimately prevail.

“Despite these minor flare-ups that happen from time to time, a good way to think about the U.S.-Canadian relationship,” he says, “is that the ability to reconcile the relationship has always outweighed any impulse toward conflict.”