Detroit /dɨˈtrɔɪt/ is the most populous city in the U.S. state of Michigan, and is the seat of Wayne County, the most populous county in the state and the largest city on the United States-Canada border. It is a primary business, cultural, financial and transportation center 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 and adventurer Antoine Laumet de La Mothe, sieur de Cadillac.
The Detroit area emerged as a significant metropolitan region within the United States as construction of a regional freeway system was completed in the 1950s and 1960s. With these commuting ties allowing social and economic integration across a larger area, the Detroit name sometimes refers to the three-county Urban Area (population 3,734,090, area of 1,337 square miles (3,460 km2), as of the 2010 United States Census), the six-county Metropolitan Statistical Area (2010 Census population of 4,296,250, area of 3,913 square miles (10,130 km2)), or the nine-county Combined Statistical Area (2010 Census population of 5,218,852, area of 5,814 square miles (15,060 km2)). The Detroit–Windsor area, a commercial link straddling the Canada–U.S. border, has a total population of about 5,700,000. The Detroit metropolitan region currently holds roughly one-half of the state's population.
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, 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's auto industry was an important element of the American "Arsenal of Democracy" supporting the Allied powers during World War II.
Between 2000 and 2010 the city's population fell by 25 percent, changing its ranking from the nation's 10th largest city to 18th. In 2010, the city had a population of 713,777, more than a 60 percent drop down from a peak population of over