The Great Lakes megalopolis consists of a bi-national group of metropolitan areas in North America largely in the Great Lakes region. It extends from the Midwestern United States in the south and west to western Pennsylvania and Western New York in the east and northward through Southern Ontario into southwestern Quebec in Canada. It is the most populated and largest megalopolis in North America.

The Great Lakes region of Northern America is a binational Canadian–American region centered around the Great Lakes that includes the U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin and the Canadian province of Ontario. Canada's Quebec province is at times included as part of the region because the St. Lawrence River watershed is part of the continuous hydrologic system. The region forms a distinctive historical, economic, and cultural identity. A portion of the region also encompasses the Great Lakes megalopolis.