22 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 17801 | Sunbury | 16,236 |
| 17847 | Milton | 11,479 |
| 17866 | Coal Township | 9,905 |
| 17872 | Shamokin | 9,157 |
| 17857 | Northumberland | 7,708 |
| 17851 | Mount Carmel | 7,232 |
| 17777 | Watsontown | 6,709 |
| 17834 | Kulpmont | 3,498 |
| 17860 | Paxinos | 2,485 |
| 17830 | Herndon | 1,971 |
| 17017 | Dalmatia | 1,516 |
| 17881 | Trevorton | 1,439 |
| 17823 | Dornsife | 1,304 |
| 17868 | Riverside | 1,057 |
| 17832 | Marion Heights | 654 |
| 17850 | Montandon | 617 |
| 17840 | Locust Gap | 363 |
| 17749 | McEwensville | 274 |
| 17836 | Leck Kill | 224 |
| 17867 | Rebuck | 191 |
| 17730 | Dewart | 47 |
| 17865 | Potts Grove | 33 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 22 ZCTAs in Northumberland County, Pennsylvania (US Census).