Parkersburg is a city in and the county seat of Wood County, West Virginia, United States. Located at the confluence of the Ohio and Little Kanawha rivers, it is the state's third-largest city and the largest city in the Parkersburg-Marietta-Vienna metropolitan area. The population was 31,492 at the 2010 census. Its peak population was 44,797 in 1960. The city is about 14 miles south of Marietta, Ohio.The Baltimore and Ohio Railroad reached Parkersburg in 1857, but lacked a crossing over the Ohio River until after the American Civil War. When the B&O completed the Parkersburg Bridge 1868–1870 to Belpre, it was the longest railroad bridge in the world.The Bureau of the Public Debt, an agency of the U.S. Treasury Department, was relocated from the Washington, D.C. metropolitan area in the late 20th century and headquartered in Parkersburg. In October 2012, it was merged with the Financial Management Service to form the Bureau of the Fiscal Service.