Founded in 1831 (boundaries declared) and 1835 (organized), Allegan County is one of 83 counties in the state of Michigan. Historically, Allegan County was formed from part of Barry County, and unorganized territory. The city of Allegan is the county seat. With FIPS code of 5, Allegan County has a population of 120,950 and area of 1,833 square miles (4,747 km2).
List of all cities in Allegan County, MI alphabetically
| City/Town | Postal Code | Area Code |
| Allegan, MI | 49010 | 269 |
| Bradley, MI | 49311 | 269 |
| Burnips, MI | 49314 | 616 |
| Dorr, MI | 49323 | 616 |
| Douglas, MI | 49406 | 269 |
| Fennville, MI | 49408 | 269 |
| Glenn, MI | 49416 | 269 |
| Hamilton, MI | 49419 | 269 |
| Hopkins, MI | 49328 | 269 |
| Martin, MI | 49070 | 269 |
| Moline, MI | 49335 | 616 |
| Otsego, MI | 49078 | 269 |
| Plainwell, MI | 49080 | 269 |
| Pullman, MI | 49450 | 269 |
| Saugatuck, MI | 49453 | 269 |
| Shelbyville, MI | 49344 | 269 |
| Wayland, MI | 49348 | 269 |