Detroit ( /diˈtrɔɪt/) is the largest city in the U.S. state of Michigan, and the seat of Wayne County. It is the major city among the primary cultural, financial, and transportation centers in the Metro Detroit area, a region of 5.2 million people, and serves as a major port on the Detroit River connecting the Great Lakes system to the Saint Lawrence Seaway. It was founded on July 24, 1701, by the French explorer, adventurer, and nobleman Antoine de la Mothe, sieur de Cadillac.
In 2010, the city had a population of 713,777 and ranked as the 18th most populous city in the United States. The name Detroit sometimes refers to the Metro Detroit area with a population of 4,296,250 for the six-county Metropolitan Statistical Area, the United States' 13th-largest, and a population of 5,218,852 for the nine-county Combined Statistical Area as of the 2010 Census. The Detroit–Windsor area, a critical commercial link straddling the Canada–U.S. border, has a total population of about 5,700,000.
Known as the world's traditional automotive center, "Detroit" is a metonym for the American automobile industry and an important source of popular music legacies celebrated by the city's two familiar nicknames, the Motor City and Motown. Other nicknames arose in the 20th century, including City of Champions beginning in the 1930s for its successes in individual and team sport, The D, D-Town, Hockeytown (a trademark owned by the city's NHL club, the Red Wings), Rock City (after the Kiss song "Detroit Rock City"), and The 313 (its telephone area code) Detroit became known as the "great arsenal of democracy" for its support of the U.S. role among the Allied powers during World War II.
Detroit and the surrounding region constitute a major center of commerce and global trade. The Detroit area emerged as a metropolitan region with construction of an extensive freeway system in the 1950s and 1960s which has expanded in ensuing decades. Freeways and transit systems have facilitated movement throughout the region with millions of people taking up residence in the suburbs. Between 2000 and 2010, the city's population fell by 25%, from the nation's 10th largest city to 18th. Commensurate with the shift of population and jobs to its suburbs, the city has had to adjust its role within the larger metropolitan area. Downtown Detroit has seen an increased role as an entertainment hub in the 21st century with the opening of three casino resort hotels, new stadiums, and a revitalized riverfront. The metropolitan region currently holds roughly one-half of the state's population.