The St. Louis, Missouri metro is home to 2.8 million people! Prior to European settlement, the St Louis area was the epicenter of Mississippi River First Peoples society. St Louis was founded in 1764 by French fur traders and named after King Louis IX. The area was won and lost by France and Spain until being sold to the US as part of the Louisiana Purchase. In 1870, St Louis was the fourth largest US city and even proclaimed itself politically independent from any nation in 1877. Today, St Louis is a Gamma Global city with more than $160 billion in annual GDP. It's headquarters to many world class corporations, including Ameren Co, Peabody Energy, Purina PetCare, Anheuser-Busch, Wells Fargo, Square, Inc., U.S. Bank, Anthem BlueCross and Blue Shield, and AT&T. Major U.S. agencies are also headquartered here, including the U.S. Department of Agriculture and National Geospatial-Intelligence Agency. Among the city's notable sights is the 630-foot (192 m) Gateway Arch in the downtown area. St. Louis is also home to the St. Louis Zoo, and the Missouri Botanical Garden, with the second-largest herbarium in North America.