Columbia is the capital city of the U.S. state of South Carolina. It is the second-most populous city in the state, with a population of 136,632 at the 2020 census, while the Columbia metropolitan area has an estimated 870,000 residents. The city serves as the county seat of Richland County, and a portion of the city extends into neighboring Lexington County and Kershaw County. The name "Columbia", a poetic term referring to the U.S., derives from the name of Christopher Columbus, who explored the Caribbean on behalf of the Spanish Empire. The name of the city is often abbreviated as "Cola", leading to its nickname "Soda City". The city, located just northwest of the geographic center of South Carolina, was the center of population of South Carolina as of 2020. It is also 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. As the state capital, Columbia is the site of the South Carolina State House, the center of government for the state. In 1860, the South Carolina Secession Convention took place in Columbia; delegates voted for secession, making South Carolina the first state to leave the Union in the events leading up to the Civil War. Columbia is home to the University of South Carolina, the state's flagship public university and the largest in the state. The area has benefited from Congressional support for military installations in the South. Columbia is the site of Fort Jackson, the largest United States Army installation for Basic Combat Training. Twenty miles to the east of the city is McEntire Joint National Guard Base, which is operated by the U.S. Air Force and is used as a training base for the 169th Fighter Wing of the South Carolina Air National Guard.