Founded in 1883, Franklin County is one of 39 counties in the state of Washington. Historically, Franklin County was formed from Whitman County. The city of Pasco is the county seat. With FIPS code of 21, Franklin County has a population of 96,749 and area of 1,242 square miles (3,217 km2).
List of all cities in Franklin County, WA alphabetically
| City/Town | Postal Code | Area Code |
| Basin City, WA | 99343 | 509 |
| Connell, WA | 99326 | 509 |
| Eltopia, WA | 99330 | 509 |
| Kahlotus, WA | 99335 | 509 |
| Mesa, WA | 99343 | 509 |
| Pasco, WA | 99301 | 509 |
| 99302 | 509 | |
| Tri Cities, WA | 99302 | 509 |