Founded in Mar 1, 1820, Allen County is one of 88 counties in the state of Ohio. Historically, Allen County was formed from Shelby County. The city of Lima is the county seat. With FIPS code of 3, Allen County has a population of 101,670 and area of 404.43 square miles (1,047 km2).
List of all cities in Allen County, OH alphabetically
| City/Town | Postal Code | Area Code |
| Beaverdam, OH | 45808 | 419/567 |
| Bluffton, OH | 45817 | 419/567 |
| Cairo, OH | 45820 | 419/567 |
| Delphos, OH | 45833 | 419/567 |
| Elida, OH | 45807 | 419/567 |
| Gomer, OH | 45809 | 419/567 |
| Harrod, OH | 45850 | 419/567 |
| Lafayette, OH | 45854 | 419/567 |
| Lima, OH | 45801 | 419/567 |
| 45802 | 419/567 | |
| 45804 | 419/567 | |
| 45805 | 419/567 | |
| 45807 | 419/567 | |
| 45809 | 419/567 | |
| 45854 | 419/567 | |
| Spencerville, OH | 45887 | 419/567 |