Pleasants County is a county located in the U.S. state of West Virginia. At the 2020 census, the population was 7,653. Its county seat is St. Marys. Pleasants County was formed by the Virginia General Assembly from portions of adjacent Wood, Ritchie and Tyler counties on March 29, 1851. The county's namesake is James Pleasants, Jr., an esteemed forme…Pleasants County is a county located in the U.S. state of West Virginia. At the 2020 census, the population was 7,653. Its county seat is St. Marys. Pleasants County was formed by the Virginia General Assembly from portions of adjacent Wood, Ritchie and Tyler counties on March 29, 1851. The county's namesake is James Pleasants, Jr., an esteemed former US Senator and Virginia Governor. On June 20, 1863, at the height of the Civil War, Pleasants County was one of fifty Virginia counties that entered the Union as the state of West Virginia.