The Quebec City–Windsor Corridor is the most densely populated and heavily industrialized region of Canada. As its name suggests, the region extends between Quebec City in the northeast and Windsor, Ontario, in the southwest, spanning 1,150 kilometres (710 mi). With more than 18 million people, it contains about half of the country's population, three of Canada's four largest metropolitan areas and seven of Canada's twelve largest metropolitan areas, all based on the 2016 census. Its relative importance to Canada's economic and political infrastructure renders it akin to the Northeast megalopolis in the United States. The name was first popularized by Via Rail, which runs frequent passenger rail service in the region in its service area known as "The Corridor".

Windsor is a city in southwestern Ontario, Canada, on the south bank of the Detroit River directly across from Detroit, Michigan, United States. Geographically located within but administratively independent of Essex County, it is the southernmost city in Canada and marks the southwestern end of the Quebec City–Windsor Corridor. The city's population was 229,660 at the 2021 census, making it the third-most populated city in Southwestern Ontario, after London and Kitchener. The Detroit–Windsor urban area is North America's most populous trans-border conurbation. Linking the Great Lakes Megalopolis, the Ambassador Bridge border crossing is the busiest commercial crossing on the Canada–United States border.