Richland County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 124,936. Its county seat is Mansfield. The county was created in 1808 and later organized in 1813. It is named for the fertile soil found there. Richland County is included in the Mansfield, OH Metropolitan Statistical Area as well as the Mansfield-Ashland-Bucyrus, OH Combined Statistical Area. The county is one of the six Metropolitan Statistical Areas that make up Northeast Ohio.

Mansfield is a city in and the county seat of Richland County, Ohio, United States. Located midway between Columbus and Cleveland via Interstate 71, it is part of Northeast Ohio region in the western foothills of the Allegheny Plateau. The 2020 Census showed that the city had a total population of 47,534, making it the 21st-largest city in Ohio. It lies approximately 65 miles (105 km) southwest of Cleveland, 45 miles (72 km) southwest of Akron and 65 miles (105 km) northeast of Columbus.