Founded in 1769, Rockingham County is one of 10 counties in the state of New Hampshire. Historically, Rockingham County was one of five original counties. The city of Brentwood is the county seat. With FIPS code of 15, Rockingham County has a population of 314,176 and area of 695 square miles (1,800 km2).
List of all cities in Rockingham County, NH alphabetically
| City/Town | Postal Code | Area Code |
| Air National Guard, NH | 03803 | 603 |
| Atkinson, NH | 03811 | 603 |
| Auburn, NH | 03032 | 603 |
| Brentwood, NH | 03833 | 603 |
| Candia, NH | 03034 | 603 |
| Chester, NH | 03036 | 603 |
| Danville, NH | 03819 | 603 |
| Deerfield, NH | 03037 | 603 |
| Derry, NH | 03038 | 603 |
| East Candia, NH | 03040 | 603 |
| East Derry, NH | 03041 | 603 |
| East Hampstead, NH | 03826 | 603 |
| East Kingston, NH | 03827 | 603 |
| Epping, NH | 03042 | 603 |
| Exeter, NH | 03833 | 603 |
| Fremont, NH | 03044 | 603 |
| Greenland, NH | 03840 | 603 |
| Hampstead, NH | 03841 | 603 |
| Hampton, NH | 03842 | 603 |
| 03843 | 603 | |
| Hampton Beach, NH | 03842 | 603 |
| 03843 | 603 | |
| Hampton Falls, NH | 03844 | 603 |
| Kensington, NH | 03833 | 603 |
| Kingston, NH | 03848 | 603 |
| Londonderry, NH | 03053 | 603 |
| New Castle, NH | 03854 | 603 |
| Newcastle, NH | 03854 | 603 |
| Newfields, NH | 03856 | 603 |
| Newington, NH | 03801 | 603 |
| Newmarket, NH | 03857 | 603 |
| Newton, NH | 03858 | 603 |
| Newton Junction, NH | 03859 | 603 |
| No Hampton, NH | 03862 | 603 |
| No Salem, NH | 03073 | 603 |
| North Hampton, NH | 03862 | 603 |
| North Salem, NH | 03073 | 603 |
| Northwood, NH | 03261 | 603 |
| Nottingham, NH | 03290 | 603 |
| Plaistow, NH | 03865 | 603 |
| Portsmouth, NH | 03801 | 603 |
| 03802 | 603 | |
| 03803 | 603 | |
| 03804 | 603 | |
| Raymond, NH | 03077 | 603 |
| Rye, NH | 03870 | 603 |
| Rye Beach, NH | 03871 | 603 |
| Salem, NH | 03079 | 603 |
| Sandown, NH | 03873 | 603 |
| Seabrook, NH | 03874 | 603 |
| So Danville, NH | 03819 | 603 |
| So Hampton, NH | 03827 | 603 |
| South Danville, NH | 03819 | 603 |
| South Hampton, NH | 03827 | 603 |
| Stratham, NH | 03885 | 603 |
| West Nottingham, NH | 03291 | 603 |
| Windham, NH | 03087 | 603 |