Columbus is the state capital and the most populous city in the U.S. state of Ohio. With …Columbus is the state capital and the most populous city in the U.S. state of Ohio. With a population of 905,748 for the 2020 census, it is the 14th-most populous city in the U.S., the second-most populous city in the Midwest after Chicago, and the third-most populous state capital. Columbus is the county seat of Franklin County; it also extends into Delaware and Fairfield counties. It is the core city of the Columbus, OH Metropolitan Statistical Area, which encompasses ten counties. The metropolitan area has a 2020 population of 2,138,926, making it the largest entirely in Ohio.