Washington County, Ohio

Washington County
Location within the U.S. state of Ohio
Ohio's location within the U.S.
Coordinates: 39°28′N 81°29′W / 39.46°N 81.49°W / 39.46; -81.49
Country United States
State Ohio
FoundedJuly 27, 1788
Named afterGeorge Washington
SeatMarietta
Largest cityMarietta
Area
  Total
640 sq mi (1,700 km2)
  Land632 sq mi (1,640 km2)
  Water8.0 sq mi (21 km2)  1.3%
Population
 (2020)
  Total
59,711
  Density93/sq mi (36/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional district6th
Websitewww.washingtongov.org

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.