17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bellingham | 1 | 96,619 | 91,871 | 0.99% | 3,426 | 28 | City |
| Lynden | 2 | 17,043 | 15,813 | 1.46% | 3,136 | 5 | City |
| Ferndale | 3 | 16,571 | 15,123 | 1.78% | 2,359 | 7 | City |
| Birch Bay | 4 | 11,824 | 9,917 | 1.96% | 692 | 17 | CDP |
| Blaine | 5 | 6,453 | 5,900 | 1.75% | 1,155 | 6 | City |
| Marietta-Alderwood | 6 | 3,154 | 3,463 | -1.56% | 542 | 6 | CDP |
| Everson | 7 | 3,153 | 2,947 | 1.32% | 2,112 | 1 | City |
| Peaceful Valley | 8 | 2,563 | 3,187 | -1.95% | 1,023 | 3 | CDP |
| Sumas | 9 | 1,704 | 1,606 | 1.19% | 1,162 | 1 | City |
| Nooksack | 10 | 1,579 | 1,479 | 1.28% | 1,817 | 1 | City |
| Point Roberts | 11 | 1,233 | 1,100 | -0.4% | 252 | 5 | CDP |
| Kendall | 12 | 1,151 | 884 | 5.89% | 419 | 3 | CDP |
| Deming | 13 | 446 | 174 | 1.59% | 162 | 3 | CDP |
| Custer | 14 | 285 | 298 | -1.72% | 127 | 2 | CDP |
| Glacier | 15 | 248 | 142 | 0.81% | 148 | 2 | CDP |
| Maple Falls | 16 | 208 | 226 | -3.7% | 97 | 2 | CDP |
| Acme | 17 | 80 | 123 | -12.09% | 53 | 1 | CDP |
Bellingham is the largest city in Whatcom County, with a population of 96,619.
Acme is the smallest city in Whatcom County, with a population of 80.
There are 17 cities in Whatcom County, Washington.