Detroit is in North America.
Detroit ( [ dᵻˈtrɔɪt ] ) is the most populous city in the U.S. state of Michigan , the largest city on the United States -- Canada border , and the seat of Wayne County . The municipality of Detroit had a 2015 estimated population of 677,116 , making it the 21st-most populous city in the United States . Detroit and its neighboring Canadian city Windsor are connected through a tunnel and the Ambassador Bridge , the busiest international crossing in North America . The United States of America ( USA ) , commonly known as the United States ( U.S. ) or America , is a constitutional federal republic composed of 50 states , a federal district , five major self-governing territories , and various possessions .