Petersburg is a city in Grant County, West Virginia, United States. The population was 2,423 at the 2000 census. It is the county seat of Grant County. Petersburg was founded circa 1745 by Jacob Peterson, who owned the area's first merchandising store. It was incorporated in 1910.
Petersburg is located at 38°59′36″N 79°7′36″W / 38.99333°N 79.12667°W / 38.99333; -79.12667 (38.993339, -79.126582).
According to the United States Census Bureau, the city has a total area of 1.6 square miles (4.2 km²), all of it land.