| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Northampton | 1 | 39,818 | 39,857 | -0.25% | 1,550 | 26 | Township |
| Easton | 2 | 30,985 | 28,066 | 1.92% | 7,268 | 4 | City |
| Palmer | 3 | 22,849 | 22,280 | 0.56% | 2,227 | 10 | Township |
| Forks | 4 | 17,093 | 16,134 | 1.27% | 1,414 | 12 | Township |
| Lower Saucon | 5 | 11,178 | 11,085 | 0.4% | 461 | 24 | Township |
| Lehigh | 6 | 11,026 | 10,767 | 0.82% | 376 | 29 | Township |
| Northampton | 7 | 10,620 | 10,365 | 0.47% | 4,298 | 2 | Borough |
| Moore | 8 | 9,545 | 9,330 | 0.39% | 257 | 37 | Township |
| Upper Nazareth | 9 | 8,575 | 8,138 | 0.63% | 1,173 | 7 | Township |
| Lower Nazareth | 10 | 7,196 | 6,930 | 0.13% | 534 | 13 | Township |
| Williams | 11 | 6,738 | 6,566 | 0.58% | 371 | 18 | Township |
| Upper Mount Bethel | 12 | 6,482 | 6,438 | 0.29% | 153 | 42 | Township |
| Hellertown | 13 | 6,142 | 6,120 | 0.07% | 4,681 | 1 | Borough |
| Nazareth | 14 | 6,100 | 6,052 | 0.15% | 3,849 | 2 | Borough |
| Allen | 15 | 5,781 | 5,474 | 1.55% | 533 | 11 | Township |
| East Allen | 16 | 5,540 | 5,013 | 1.24% | 381 | 15 | Township |
| Bangor | 17 | 5,112 | 5,142 | -0.12% | 3,426 | 1 | Borough |
| Wind Gap | 18 | 3,830 | 2,817 | 5.51% | 2,860 | 1 | Borough |
| Pen Argyl | 19 | 3,458 | 3,502 | -0.29% | 2,577 | 1 | Borough |
| Lower Mount Bethel | 20 | 2,926 | 2,917 | 0.1% | 123 | 24 | Township |
| Bath | 21 | 2,918 | 2,843 | 0.52% | 3,231 | 1 | Borough |
| Walnutport | 22 | 2,102 | 2,072 | 0.24% | 2,795 | 1 | Borough |
| Roseto | 23 | 1,599 | 1,619 | -0.25% | 2,542 | 1 | Borough |
| Tatamy | 24 | 1,439 | 1,187 | 3.6% | 2,593 | 1 | Borough |
| East Bangor | 25 | 1,098 | 1,110 | -0.27% | 1,321 | 1 | Borough |
| Stockertown | 26 | 917 | 919 | -0.11% | 945 | 1 | Borough |
| Portland | 27 | 484 | 486 | -0.21% | 1,002 | 0 | Borough |
| Northampton | 28 | 290 | 304 | -0.68% | 8.0 | 36 | Township |
| Chapman | 29 | 221 | 220 | 0% | 670 | 0 | Borough |
Northampton is the largest city in Northampton County, with a population of 39,818.
Chapman is the smallest city in Northampton County, with a population of 221.
There are 29 cities in Northampton County, Pennsylvania.