Washington County is a county located in the southeastern part of the U.S. state of Ohio. As of the 2020 census, the population was 59,711. Its county seat is Marietta. The county, the oldest in the state, is named for George Washington. Washington County comprises the Marietta, OH Micropolitan Statistical Area, which is also included in the Parkersburg-Marietta-Vienna, WV-OH Combined Statistical Area.

Ohio's 6th congressional district was represented by Representative Bill Johnson (R-OH) until his resignation in 2024. This district runs along the eastern side of the state, bordering West Virginia, and Pennsylvania. It stretches from Marietta through several Ohio River industrial towns all the way to the city of Youngstown.