Founded in Apr 1, 1820, Williams County is one of 88 counties in the state of Ohio. Historically, Williams County was formed from Darke County. The city of Bryan is the county seat. With FIPS code of 171, Williams County has a population of 36,716 and area of 421.74 square miles (1,092 km2).
List of all cities in Williams County, OH alphabetically
| City/Town | Postal Code | Area Code |
| Alvordton, OH | 43501 | 419/567 |
| Archbold, OH | 43570 | 419/567 |
| Blakeslee, OH | 43505 | 419/567 |
| Bryan, OH | 43506 | 419/567 |
| Edgerton, OH | 43517 | 419/567 |
| Edon, OH | 43518 | 419/567 |
| Evansport, OH | 43557 | 419/567 |
| Holiday City, OH | 43543 | 419/567 |
| 43554 | 419/567 | |
| Kunkle, OH | 43531 | 419/567 |
| Montpelier, OH | 43543 | 419/567 |
| Pioneer, OH | 43554 | 419/567 |
| Stryker, OH | 43557 | 419/567 |
| West Unity, OH | 43570 | 419/567 |