Clay is a town in and the county seat of Clay County, West Virginia, United States. The population was 399 at the 2020 census. It is the only incorporated town in Clay County. Clay was established on the site of a farm that was the site of Clay County's first court meeting following the county's establishment in 1858. The community was initially known b…Clay is a town in and the county seat of Clay County, West Virginia, United States. The population was 399 at the 2020 census. It is the only incorporated town in Clay County. Clay was established on the site of a farm that was the site of Clay County's first court meeting following the county's establishment in 1858. The community was initially known by the name of "Marshall," then briefly as "Henry," and then as "Clay Courthouse" and finally Clay. The town and county are both named for U.S. Senator and Secretary of State Henry Clay. The town was incorporated in 1895. Before 1880, Clay was inaccessible to traffic from horse-drawn vehicles, and the Elk River was its primary mode of transport. Expansion of the Coal and Coke Railway reached Clay in 1905.