Grant County is a county located in the U.S. state of West Virginia. As of the 2010 census, the population was 11,937. Its county seat is Petersburg. The county was created from Hardy County in 1866 and named for General Ulysses Simpson Grant. After the American Civil War, there was an effort by former Confederates to name it 'Lee County' instead after General Robert E. Lee, but the effort proved fruitless.