Salem is a city in northern Columbiana County, Ohio, United States. The population was 11,915 at the 2020 census. It extends into southern …Salem is a city in northern Columbiana County, Ohio, United States. The population was 11,915 at the 2020 census. It extends into southern Mahoning County and is the principal city of the Salem micropolitan area. Salem was founded by Quakers in 1806 and played a key role in the abolitionist movement as a hub of the Underground Railroad. Once an industrial town, Salem is now a commuter town and regional economic center, home to Allegheny Wesleyan College and Kent State University at Salem.