Founded in Mar 6, 1840, Ottawa County is one of 88 counties in the state of Ohio. Historically, Ottawa County was formed from Erie, Sandusky, and Lucas Counties. The city of Port Clinton is the county seat. With FIPS code of 123, Ottawa County has a population of 40,104 and area of 254.95 square miles (660 km2).
List of all cities in Ottawa County, OH alphabetically
| City/Town | Postal Code | Area Code |
| Bono, OH | 43445 | 419/567 |
| Catawba Island, OH | 43452 | 419/567 |
| Clay Center, OH | 43408 | 419/567 |
| Curtice, OH | 43412 | 419/567 |
| Elliston, OH | 43432 | 419/567 |
| Elmore, OH | 43416 | 419/567 |
| Genoa, OH | 43430 | 419/567 |
| Graytown, OH | 43432 | 419/567 |
| Gypsum, OH | 43433 | 419/567 |
| Is St George, OH | 43436 | 419/567 |
| Isle Saint George, OH | 43436 | 419/567 |
| Isle St George, OH | 43436 | 419/567 |
| Lacarne, OH | 43439 | 419/567 |
| Lakeside, OH | 43440 | 419/567 |
| Lakeside Marblehead, OH | 43440 | 419/567 |
| Lksid Marblhd, OH | 43440 | 419/567 |
| Marblehead, OH | 43440 | 419/567 |
| Martin, OH | 43445 | 419/567 |
| Middle Bass, OH | 43446 | 419/567 |
| 43452 | 419/567 | |
| Oak Harbor, OH | 43449 | 419/567 |
| Point Clinton, OH | 43452 | 419/567 |
| Port Clinton, OH | 43446 | 419/567 |
| 43452 | 419/567 | |
| Put in Bay, OH | 43456 | 419/567 |
| Reno Beach, OH | 43412 | 419/567 |
| Rocky Ridge, OH | 43458 | 419/567 |
| Williston, OH | 43468 | 419/567 |