Founded in 1772, Northumberland County is one of 67 counties in the state of Pennsylvania. Historically, Northumberland County was formed from parts of Lancaster, Berks, Bedford, Cumberland, and Northampton Counties. The city of Sunbury is the county seat. With FIPS code of 97, Northumberland County has a population of 91,266 and area of 477 square miles (1,235 km2).
List of all cities in Northumberland County, PA alphabetically
| City/Town | Postal Code | Area Code |
| Anthony, PA | 17772 | 570 |
| Atlas, PA | 17851 | 570 |
| Augustaville, PA | 17801 | 570 |
| Bear Gap, PA | 17824 | 570 |
| Bear Valley, PA | 17872 | 570 |
| Boydtown, PA | 17872 | 570 |
| Camp Grove, PA | 17830 | 570 |
| Chillisquaque, PA | 17850 | 570 |
| Coal, PA | 17872 | 570 |
| Coal Run, PA | 17866 | 570 |
| Coal Township, PA | 17866 | 570 |
| Comly, PA | 17772 | 570 |
| Connersville, PA | 17851 | 570 |
| Dalmatia, PA | 17017 | 570 |
| Delaware Run, PA | 17777 | 570 |
| Dewart, PA | 17730 | 570 |
| Diamondtown, PA | 17851 | 570 |
| Dooleyville, PA | 17851 | 570 |
| Dornsife, PA | 17823 | 570 |
| Doutyville, PA | 17872 | 570 |
| Dunkelbergers, PA | 17872 | 570 |
| East Chillisquaq, PA | 17847 | 570 |
| East Lewisburg, PA | 17847 | 570 |
| Elysburg, PA | 17824 | 570 |
| Excelsior, PA | 17866 | 570 |
| Fisherdale, PA | 17824 | 570 |
| Fishers Ferry, PA | 17801 | 570 |
| Goosetown, PA | 17777 | 570 |
| Gowen City, PA | 17872 | 570 |
| Greenbrier, PA | 17867 | 570 |
| Happy Valley, PA | 17824 | 570 |
| Hebe, PA | 17830 | 570 |
| Herndon, PA | 17830 | 570 |
| Hunter, PA | 17872 | 570 |
| Island Park, PA | 17801 | 570 |
| Kapp Heights, PA | 17857 | 570 |
| Klines Grove, PA | 17801 | 570 |
| Knoebels Grv, PA | 17824 | 570 |
| Kulpmont, PA | 17834 | 570 |
| Leck Kill, PA | 17836 | 570 |
| Leckkill, PA | 17836 | 570 |
| Limestonevle, PA | 17847 | 570 |
| Lithia Sprs, PA | 17857 | 570 |
| Little Mahany, PA | 17823 | 570 |
| Locust Gap, PA | 17840 | 570 |
| Lower Augusta, PA | 17801 | 570 |
| Luke Fidler, PA | 17872 | 570 |
| Mandata, PA | 17830 | 570 |
| Marion Height, PA | 17832 | 570 |
| Marion Heights, PA | 17832 | 570 |
| Marshallton, PA | 17872 | 570 |
| Mc Ewensville, PA | 17749 | 570 |
| McEwensville, PA | 17749 | 570 |
| Meadowview, PA | 17860 | 570 |
| Merrian, PA | 17851 | 570 |
| Mile Hill, PA | 17801 | 570 |
| Mile Run, PA | 17801 | 570 |
| Milton, PA | 17847 | 570 |
| Montandon, PA | 17850 | 570 |
| Mount Carmel, PA | 17851 | 570 |
| Natalie, PA | 17851 | 570 |
| Northumberland, PA | 17857 | 570 |
| Oak Park, PA | 17857 | 570 |
| Oaklyn, PA | 17801 | 570 |
| Paxinos, PA | 17860 | 570 |
| Potts Grove, PA | 17865 | 570 |
| Ralpho, PA | 17872 | 570 |
| Ranshaw, PA | 17866 | 570 |
| Rebuck, PA | 17867 | 570 |
| Red Cross, PA | 17823 | 570 |
| Reed Station, PA | 17860 | 570 |
| Reeders Grove, PA | 17824 | 570 |
| Riverside, PA | 17868 | 570 |
| Rockefeller, PA | 17801 | 570 |
| Sagon, PA | 17872 | 570 |
| Schuyler, PA | 17772 | 570 |
| Sevenpoints, PA | 17801 | 570 |
| Shamokin, PA | 17872 | 570 |
| Snydertown, PA | 17877 | 570 |
| Stonington, PA | 17801 | 570 |
| Strong, PA | 17851 | 570 |
| Sunbury, PA | 17801 | 570 |
| 17877 | 570 | |
| Sunnyside, PA | 17872 | 570 |
| Tharptown, PA | 17872 | 570 |
| Trevorton, PA | 17881 | 570 |
| Turbotville, PA | 17772 | 570 |
| Upper Augusta, PA | 17801 | 570 |
| Upper Mahanoy, PA | 17836 | 570 |
| Urban, PA | 17830 | 570 |
| Watsontown, PA | 17777 | 570 |
| Watsonville, PA | 17777 | 570 |
| Weigh Scale, PA | 17872 | 570 |
| West Cameron, PA | 17872 | 570 |
| West Chillisquaq, PA | 17850 | 570 |
| Wolverton, PA | 17868 | 570 |