Founded on Dec 21, 1837, Clayton County is one of 99 counties in the state of Iowa. Historically, Clayton County was formed from Dubuque County and Wisconsin Territory. The city of Elkader is the county seat. With FIPS code of 43, Clayton County has a population of 16,998 and area of 779 square miles (2,018 km2).
List of all cities in Clayton County, IA alphabetically
| City/Town | Postal Code | Area Code |
| Clayton, IA | 52049 | 563 |
| Clayton Center, IA | 52043 | 563 |
| Communia, IA | 52043 | 563 |
| Edgewood, IA | 52042 | 563 |
| 52044 | 563 | |
| Elkader, IA | 52043 | 563 |
| Elkport, IA | 52044 | 563 |
| Farmersburg, IA | 52047 | 563 |
| Froelich, IA | 52047 | 563 |
| Garber, IA | 52048 | 563 |
| Garnavillo, IA | 52049 | 563 |
| Giard, IA | 52157 | 563 |
| Guttenberg, IA | 52052 | 563 |
| Hardin, IA | 52156 | 563 |
| Holy Cross, IA | 52066 | 563 |
| Littleport, IA | 52042 | 563 |
| Luana, IA | 52156 | 563 |
| Marquette, IA | 52158 | 563 |
| Mc Gregor, IA | 52157 | 563 |
| Mederville, IA | 52043 | 563 |
| Millville, IA | 52052 | 563 |
| Monona, IA | 52159 | 563 |
| National, IA | 52047 | 563 |
| North Buena Vista, IA | 52066 | 563 |
| Osborne, IA | 52043 | 563 |
| Rossville, IA | 52159 | 563 |
| Saint Olaf, IA | 52072 | 563 |
| Strawberry Point, IA | 52076 | 563 |
| Turkey River, IA | 52052 | 563 |
| Volga, IA | 52077 | 563 |
| Volney, IA | 52159 | 563 |
| Watson, IA | 52159 | 563 |
| Wood, IA | 52042 | 563 |