Watertown is an unincorporated community in southwestern Watertown Township, Washington County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 45787. It lies near the intersection of State Routes 339 and 676 near Wolf Creek, which meets the Muskingum River at Waterford to the north. In 1986, the community was listed on the National Register of Historic Places in 1986 as a historic district, the "Watertown Historic District. " The district includes examples of the Stick/Eastlake and Queen Anne architectural styles.