McDowell County is a county in the U.S. state of West Virginia. As of the 2020 census, the population was 19,111. Its county seat is Welch. McDowell County is the southernmost county in the state. It was created in 1858 by the Virginia General Assembly and named for Virginia Governor James McDowell. It became a part of West Virginia in 1863, when several Union-affiliated counties seceded from the state of Virginia during the American Civil War. McDowell County is located in the Cumberland Mountains, part of the Appalachia region.