Williamstown is a borough in Dauphin County, Pennsylvania, 38 miles (61 km) northeast of Harrisburg. Formerly, Anthracite coal mines were here, as well as hosiery mills. In 1900, 2,904 people lived here, and 2,934 lived here in 1910. The population was 1,433 at the 2000 census. Williamstown is part of the Harrisburg–Carlisle Metropolitan Statistical Area.