Founded in 1915, Boundary County is one of 44 counties in the state of Idaho. Historically, Boundary County was formed from Bonner County. The city of Bonners Ferry is the county seat. With FIPS code of 21, Boundary County has a population of 12,561 and area of 1,269 square miles (3,287 km2).
List of all cities in Boundary County, ID alphabetically
| City/Town | Postal Code | Area Code |
| Bonners Ferry, ID | 83805 | 208 |
| Copeland, ID | 83805 | 208 |
| Eastport, ID | 83826 | 208 |
| Moyie Springs, ID | 83845 | 208 |
| Naples, ID | 83847 | 208 |
| Porthill, ID | 83853 | 208 |