Columbia is the capital and largest city of the U.S. state of South Carolina, with a population of 133,803 as of 2015. The city serves as the county seat of Richland County, and a portion of the city extends into neighboring Lexington County. It is the center of the Columbia metropolitan statistical area, which had a population of 767,598 as of the 2010 United States Census, growing to 810,068 by July 1, 2015, according to 2015 U.S. Census estimates. The name Columbia is a poetic term used for the United States, originating from the name of Christopher Columbus.The city is located approximately 13 miles (21 km) northwest of the geographic center of South Carolina, and is the primary city of the Midlands region of the state. It lies at the confluence of the Saluda River and the Broad River, which merge at Columbia to form the Congaree River. Columbia is home to the University of South Carolina, the state's flagship and largest university, and is also the site of Fort Jackson, the largest United States Army installation for Basic Combat Training. In 1860, the city was the location of the South Carolina Secession Convention, which marked the departure of the first state from the Union in the events leading up to the Civil War.