| Zip Code | City | Population ↓ |
|---|---|---|
| 18042 | Easton | 44,818 |
| 18017 | Bethlehem | 40,587 |
| 18015 | Bethlehem | 33,472 |
| 18045 | Easton | 29,563 |
| 18064 | Nazareth | 27,112 |
| 18020 | Bethlehem | 21,153 |
| 18067 | Northampton | 19,166 |
| 18013 | Bangor | 17,962 |
| 18040 | Easton | 17,090 |
| 18014 | Bath | 12,389 |
| 18055 | Hellertown | 11,796 |
| 18088 | Walnutport | 8,118 |
| 18072 | Pen Argyl | 6,937 |
| 18091 | Wind Gap | 5,888 |
| 18343 | Mount Bethel | 3,964 |
| 18038 | Danielsville | 3,466 |
| 18085 | Tatamy | 887 |
| 18351 | Portland | 606 |
| 18083 | Stockertown | 594 |
| 18086 | Treichlers | 521 |
| 18063 | Martins Creek | 280 |
| 18035 | Cherryville | 25 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 22 ZCTAs in Northampton County, Pennsylvania (US Census).