Columbus is the capital and most populous city of the U.S. state of Ohio. With a 2020 census population of 905,748, 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 U.S. state capital after Phoenix, Arizona and Austin, Texas. Columbus is the seat of government of Franklin County; it also extends into Delaware and Fairfield counties. It is the core city of the Columbus metropolitan area, which encompasses ten counties in central Ohio. It had a population of 2,138,926 in 2020, making it the largest metropolitan area entirely in Ohio and 32nd-largest metro area in the U.S.

Delaware County is a county located in the central portion of the U.S. state of Ohio. As of the 2020 census, the population was 214,124. Its county seat and largest city is Delaware.