Marion is a city in and the county seat of Marion County, Ohio, United States. The municipality is located in north-central Ohio, approximately 50 miles north of Columbus.
The population was 36,837 at the 2010 census, and is estimated to be 35,883 in 2019. It is the largest city in Marion County and the principal city of the Marion, OH Micropolitan Statistical Area. It is also part of the larger Columbus–Marion–Zanesville, OH Combined Statistical Area, which has 2,481,525 people according to the US Census 2017 estimate. President Warren G. Harding, a former owner of the Marion Star, was a resident of Marion for much of his adult life and is buried at Harding Tomb.
The city and its development were closely related to industrialist Edward Huber and his extensive business interests. The city is home to several historic properties, some listed on the National Register of Historic Places listings in Marion County, Ohio.