St. Louis City is an independent city and a major United States port in eastern Missouri. The city was developed along the western bank of the Mississippi River, which forms Missouri's eastern border with Illinois. At the 2010 census, St. Louis' population was 319,294 and a 2013 estimate put the population at 456,967, making it the 58th-most populous U.S. city in 2013 and the second-largest city in the state. The St. Louis metropolitan area, known as Greater St. Louis (CSA), includes the city as well as nearby areas in Missouri and Illinois; it is among the 13th largest metropolitan areas in the United States with a population of 2,905,893. The St. Louis metropolitan area is the largest metropolitan area in the state of Missouri.
The city of St. Louis was founded in 1764 by Pierre Laclède and Auguste Chouteau and named after Louis IX of France. After the Louisiana Purchase, it became a major port on the Mississippi River. In the late 19th century, St. Louis became the fourth-largest city in the United States. It seceded from St. Louis County in March 1877, allowing it to become an independent city and limiting its political boundaries. In 1904, it hosted the Louisiana Purchase Exposition and the 1904 Summer Olympics. The city's population peaked in 1950; with restructuring of heavy industry and loss of jobs, plus postwar suburbanization, it began a long decline that continues in the 21st century. Immigration has increased, and the city is the center of the largest Bosnian population in the world outside their homeland.
The economy of St. Louis relies on service, manufacturing, trade, transportation of goods, and tourism. The city is home to several major corporations including Express Scripts, Peabody Energy, Ameren, Ralcorp, and Sigma-Aldrich. St. Louis is also home to three professional sports teams: the St. Louis Cardinals—one of the most successful Major League Baseball clubs, the St. Louis Blues of the National Hockey League, and the St. Louis Rams of the National Football League. The city is commonly identified with the 630-foot (192 m) tall Gateway Arch, which is part of the Jefferson National Expansion Memorial in downtown St. Louis.