Lorain County is a county in the northeastern part of the U.S. state of Ohio As of the 2020 census, the population was 312,964. Its county seat is Elyria, and its largest city is Lorain. The county was physically established in 1822, becoming judicially independent in 1824. Lorain County is part of the Cleveland, OH Metropolitan Statistical Area. The county is home to Oberlin College.