Founded in 1803, Coös County is one of 10 counties in the state of New Hampshire. Historically, Coös County was formed from part of Grafton County. The city of Lancaster is the county seat. With FIPS code of 7, Coös County has a population of 31,268 and area of 1,801 square miles (4,665 km2).
List of all cities in Coos County, NH alphabetically
| City/Town | Postal Code | Area Code |
| Berlin, NH | 03570 | 603 |
| Bretton Woods, NH | 03575 | 603 |
| Carroll, NH | 03598 | 603 |
| Clarksville, NH | 03592 | 603 |
| Colebrook, NH | 03576 | 603 |
| Columbia, NH | 03576 | 603 |
| 03590 | 603 | |
| Dalton, NH | 03598 | 603 |
| Dixville, NH | 03576 | 603 |
| Dixville Notch, NH | 03576 | 603 |
| Dummer, NH | 03588 | 603 |
| Errol, NH | 03579 | 603 |
| Gorham, NH | 03581 | 603 |
| Groveton, NH | 03582 | 603 |
| Jefferson, NH | 03583 | 603 |
| Lancaster, NH | 03584 | 603 |
| Milan, NH | 03588 | 603 |
| Mount Washington, NH | 03589 | 603 |
| No Stratford, NH | 03590 | 603 |
| North Stratford, NH | 03590 | 603 |
| Northumberland, NH | 03582 | 603 |
| 03583 | 603 | |
| 03584 | 603 | |
| Pittsburg, NH | 03592 | 603 |
| Randolph, NH | 03593 | 603 |
| Shelburne, NH | 03581 | 603 |
| Stark, NH | 03582 | 603 |
| Stewartstown, NH | 03576 | 603 |
| Stratford, NH | 03590 | 603 |
| Twin Mountain, NH | 03595 | 603 |
| Wentworths Location, NH | 03579 | 603 |
| West Stewartstown, NH | 03597 | 603 |
| Whitefield, NH | 03598 | 603 |