Canada and the United States share the longest international border in the world, with its 8,891 kilometres stretching from New Brunswick to the Yukon. For centuries, the border has been crossed for purposes of industry and trade. Individuals, too, have travelled from one country to the other for work, vacation, to visit family, or other purposes.

Historically, people have crossed this border for myriad reasons. British loyalists—and Indigenous people who fought alongside them—fled to Canada after the American Revolution, as did enslaved individuals, who followed the Underground Railroad to seek liberty and safety. Bootleggers smuggled liquor into the United States during Prohibition, and by 1930, almost a million French Canadians had crossed the border to find work in New England mills. In addition, countless immigrants stopped first in Canada before continuing on to the United States.

While many Canada-U.S. border crossings took place before government officials began recording them, understanding how the border changed over the years may give you some helpful context as you look into your family history.

Historical Changes to the Canada-U.S. Border

The United States-Canada border, as it exists today, only dates to 1903. It formed as a result of centuries of colonization, war, and diplomacy between French and English powers as well as land acquisition through treaties with Indigenous peoples.

French explorers were the first Europeans to settle permanently in Canada, and in 1608, Samuel de Champlain built Fort Saint-Louis where Quebec City now stands. In the following decades, French claims expanded beyond the fort, while England established colonies farther south along the Atlantic Coast and in the Maritimes, landing in Nova Scotia, Newfoundland, and New Brunswick. France and England had long been rivals in Europe, and their disputes extended to North America as they struggled to control the North American continent.

After Queen Anne's War (1702-13), Britain gained the territories of Nova Scotia, Newfoundland, and the Hudson Bay region. In 1763, after prevailing in the French and Indian War, called "La guerre de la Conquête" in French-speaking Canada, Britain gained nearly all French territory east of the Mississippi River. This event also set the stage for Indigenous people to have their lands taken from them as the British sought new opportunities to expand settlements along the colonial frontier.

The American Revolution led to further bloodshed along the border, as the American colonists tried and failed to capture Quebec, Montreal, and Nova Scotia. When the Americans won the war, the Treaty of Paris established the border between the United States and British North America. In doing so, however, they disregarded the treaties already in place with Indigenous communities along the boundary line. In the north of the newly established United States, the border was marked by the Great Lakes, the St. Lawrence River, and the 45th parallel—all the way east through Vermont. In New Brunswick and Quebec, the squiggly line that separates those provinces from Maine and New Hampshire follows rivers, lakes, and a meandering natural ridge.

As British Canada and the United States grew to the west, the two countries extended the border. It stretched along the 49th parallel, from Minnesota’s Lake of the Woods in the east to the Strait of Georgia next to British Columbia in the west—roughly from Winnipeg, Manitoba, to Vancouver, British Columbia. Native nations on either side of the border were not consulted when this new boundary was established, leading to disruption, displacement, and even the destruction of their homes and ways of life. The current land border between Canada and the lower 48 U.S. states has been in place since the Oregon Treaty of 1846.

Canada originally shared its western border with Russia, which had a colony in Alaska for 80 years. The two nations agreed on a boundary line in 1825 that roughly follows the Yukon River Valley and the 141st meridian. But after the United States purchased Alaska in 1867, it disputed the border on the southeastern coast. An international tribunal settled the matter in favour of the United States in 1903, awarding it the skinny stretch of coast known as the Alaska Panhandle. The Alaska portion of the U.S.-Canada border is 2,349 kilometres long.

Building Bridges to Help Cross-Border Movement

Despite all of the conflict surrounding the border, Canada and the United States have often worked together to build roads, bridges, and canals along it to streamline trade and the movement of people. In the 19th century, Britain was Canada's largest trading partner, but it still exported lumber, fish, and agricultural products to the United States and imported manufactured goods. If your ancestors lived in those border areas, could they have been involved in one of those building projects? Might they have worked to transport goods across the border?

The earliest infrastructure projects to facilitate cross-border movement were in the east. Since 1848, the two countries have built multiple bridges near Niagara Falls. These include a railway suspension bridge and the steel-arch Honeymoon Bridge, which collapsed after 40 years of heavy ice and high winds. The Rainbow Bridge opened in 1940 and still operates today; its name symbolises the friendship between Canada and the United States. As Niagara Falls has long been a popular honeymoon destination, maybe your great-grandparents, newlyweds in 1950, crossed one of those bridges during their visit to see the sights in the other country?

Increased shipping and passenger demands in the 1920s and 1930s prompted the building of the Ambassador Bridge between Windsor and Detroit (1929), the 1,572-metre Windsor and Detroit Tunnel (1930), which travels underwater between Ontario and Michigan, and the Thousand Islands Bridge (1938), a 13,700-kilometre five-bridge system that travels across the St. Lawrence River between Ontario and New York.

Historical Canada-U.S. Border Crossing Locations

Border crossing locations have often been next to lakes and rivers that span the two countries. Yet many travellers also sailed into ports on the Atlantic and Pacific Oceans.

As you look for records of your ancestors’ cross-border travel, you may discover that they regularly passed between Saint-Armand, Quebec and St. Albans, Vermont for work in one of the mills, quarries, or factories during the 1930s, for example. Other common points of entry between the two countries:

• Queenston, Ontario and Lewiston, New York on the Niagara River
• Neebing, Ontario and Grand Portage-Pigeon River, Minnesota on Lake Superior
• Fort Erie, Ontario and Buffalo, New York
• Windsor, Ontario, and Detroit, Michigan
• Coutts, Alberta and Sweet Grass, Montana
• Surrey, British Columbia and Blaine, Washington

Evolving Canada-U.S. Border Crossing Requirements

For most of the 19th century, people could move freely across the border between Canada and the United States—officials weren’t in place to document the crossings. Emigrants from overseas who wanted to go to the United States, but who wished to avoid inspection at ports like Ellis Island in New York, might choose to travel by land from Canada. In fact, steamship companies promoted the Canadian route as a hassle-free way to get to the United States. The U.S. government finally caught on, and in 1895, it began placing border services officers along the boundary with Canada, who began to record the entries. Canada started recording information about travellers crossing from the United States in 1908.

Questions Inspectors Asked at Border Crossings: Insights for Family Historians

Whether arriving by ship in Quebec, Halifax, or Victoria, or crossing the border into St. Albans, Vermont, or Windsor, Ontario, immigration officers often asked foreign nationals detailed questions, such as:

• Age
• Place of birth
• Marital status
• Occupation
• Nationality
• Race
• Religion
• Destination
• The name and address of their nearest relative
• If the person or family member had a health condition or mental illness
• The amount of money in their possession
• Whether or not they’d been in Canada before

Before 1906, U.S. records only exist for foreign nationals who crossed the border, not people born in Canada. After 1906, Canadian-born immigrants were documented in U.S. records well.

How to Learn About Family Members Who Crossed the Canada-U.S. Border

Did a branch of your family live in the United States before moving to Canada? Or vice versa? Might a family member’s occupation have caused them to cross regularly between the two countries? Did your family members travel by foot, boat, train, car, or plane? Ancestry^® can help you find stories about your family from both sides of the border.

The Ancestry^® card catalogue contains extensive records related to border crossings, so you may want to narrow your search using filters like nationality or birthplace, or by browsing a specific database. If your ancestors crossed back and forth between Quebec and the United States, you may also find records in French.

• Search records of border crossings into the United States. The database Border Crossings from Canada to the U.S., which covers 1895-1960, has records for dozens of ports of entry from Maine to Washington State. The information on the records varies, but it generally includes a person's nationality, birthplace, and birthdate, as well as the names of their closest relatives in their home country and at their U.S. destination. Some even include a photograph. The dataset for Detroit, Michigan, Border Crossings (1905-1963) is one of the largest location-specific collections in this topic category (for the United States), containing more than 1.7 million records.
• Explore Canadian immigration records. In 1908, the Government of Canada began recording the names of immigrants who crossed the border from the United States. These border crossing records only go until 1935, but they can be quite detailed, covering a person's language, religion, and purpose in coming to Canada.
• Check passenger and crew lists. Canada's incoming passenger lists recorded everyone onboard the ships arriving in major ports from 1865-1935. These records can include whether your relatives could read or write, where they embarked, and if they intended to become permanent residents of Canada. You can find similar information on the passenger and crew lists for U.S.-bound vessels that arrived in Canada.
• Browse lists of airline passengers. If your relatives were lucky enough to fly in the mid-20th century, they could appear on airline passenger and crew lists. A database for planes landing in Washington State, for example, spans 1947-1957 and includes the date of arrival and previous residence.

Explore Your Family's Border Crossing Story

Find out if your ancestors sought to establish new roots on one side of the border or whether they crossed back and forth. Discover family stories from Canada, the United States, and beyond through immigration records on Ancestry today.