St. Louis ( or ) is a cityMissouri QuickFacts from the US Census Bureau. and port in the U.S. state of Missouri. The city developed along the western bank of the Mississippi River, which forms Missouri’s border with Illinois. In 2010, St. Louis had a population of 319,294; a 2013 estimate put the population at 318,416, making it the 58th-most populous U.S. city in 2013 and the second-largest city in the state. The St. Louis metropolitan area includes the city as well as nearby areas in Missouri and Illinois; it is among the largest metropolitan areas in the United States, with a population of 2,905,893. St. Louis was founded in 1764 by Pierre Laclède and Auguste Chouteau and named after Louis IX of France. The region in which the city stands was part of Spanish Louisiana from 1762 until 1802. 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 1877, becoming an independent city and limiting its political boundaries. In 1904, it hosted the Louisiana Purchase Exposition and the 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 continued into 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, Monsanto, Ralcorp, and Sigma-Aldrich. St. Louis is also home to three professional sports teams: the St. Louis Cardinals of Major League Baseball, 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 tall Gateway Arch in downtown St. Louis.