High Quality Content by WIKIPEDIA articles! The City of Delaware is a city in and the county seat of Delaware County in the United States state of Ohio. Delaware was founded in 1808 and was incorporated in 1816. It is located near the center of Ohio, is about 20 miles (32 km) north of Columbus, and is part of the Columbus, Ohio Metropolitan Area. The population was 34,753 at the 2010 census, while the Columbus-Marion-Chillicothe, OH Combined Statistical Area has 2,002,604 people.