Founded in Jul 27, 1788, Washington County is one of 88 counties in the state of Ohio. Historically, Washington County was one of the original counties. The city of Marietta is the county seat. With FIPS code of 167, Washington County has a population of 59,423 and area of 635.15 square miles (1,645 km2).
List of all cities in Washington County, OH alphabetically
| City/Town | Postal Code | Area Code |
| Barlow, OH | 45712 | 740 |
| Bartlett, OH | 45713 | 740 |
| Belpre, OH | 45714 | 740 |
| Beverly, OH | 45715 | 740 |
| 45721 | 740 | |
| Coal Run, OH | 45715 | 740 |
| 45721 | 740 | |
| Cutler, OH | 45724 | 740 |
| Dungannon, OH | 45721 | 740 |
| Elba, OH | 45746 | 740 |
| Fleming, OH | 45729 | 740 |
| Fly, OH | 45767 | 740 |
| Graysville, OH | 45734 | 740 |
| Little Hocking, OH | 45742 | 740 |
| Lowell, OH | 45744 | 740 |
| Lower Salem, OH | 45745 | 740 |
| Macksburg, OH | 45746 | 740 |
| Marietta, OH | 45750 | 740 |
| Matamoras, OH | 45767 | 740 |
| New Matamoras, OH | 45734 | 740 |
| 45767 | 740 | |
| 45789 | 740 | |
| Newport, OH | 45768 | 740 |
| Reno, OH | 45773 | 740 |
| Rinard Mills, OH | 45734 | 740 |
| 45767 | 740 | |
| Vincent, OH | 45784 | 740 |
| Warner, OH | 45745 | 740 |
| Waterford, OH | 45786 | 740 |
| Watertown, OH | 45787 | 740 |
| Whipple, OH | 45788 | 740 |
| Wingett Run, OH | 45789 | 740 |