Clarksburg is a city in and the county seat of Harrison County, West Virginia, United States, in the north-central region of the state. The p…Clarksburg is a city in and the county seat of Harrison County, West Virginia, United States, in the north-central region of the state. The population of the city was 16,039 at the 2020 census, making it the tenth-most populous city in West Virginia. It is the principal city of the Clarksburg micropolitan area, which had a population of 90,434 in 2020. Clarksburg was named National Small City of the Year in 2011 by the National League of Cities.