Marietta, city, seat of Washington County, southeastern Ohio, at the confluence of the Muskingum and Ohio rivers; incorporated 1852. It is a trade and manufacturing center situated in an agricultural region. Major products include metal and plastic items, petroleum and natural-gas drilling equipment, chemicals, glassware, and building materials. Marietta is the site of Marietta College (1834), a community college, the Ohio River Museum (1974), Campus Martius: The Museum of the Northwest Territory (1919), and Mound Cemetery, a prehistoric Native American burial mound that also contains the graves of 24 officers of the American Revolution. Marietta, named for Queen Marie-Antoinette of France in recognition of French aid to the United States during the American Revolution, was settled in 1788 and is the oldest permanent community in Ohio. In 1788 it also became the first capital of the Northwest Territory. Population 16,467 (1980); 15,026 (1990); 14,515 (2000).
