7 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bellingham | 1 | 96,857 | 91,870 | 1.04% | 3,435 | 28 | City |
| Ferndale | 2 | 17,096 | 15,146 | 2.33% | 2,374 | 7 | City |
| Lynden | 3 | 17,027 | 15,806 | 1.45% | 3,133 | 5 | City |
| Blaine | 4 | 6,488 | 5,901 | 1.84% | 1,161 | 6 | City |
| Everson | 5 | 3,223 | 2,950 | 1.7% | 2,159 | 1 | City |
| Nooksack | 6 | 1,719 | 1,499 | 2.63% | 1,871 | 1 | City |
| Sumas | 7 | 1,702 | 1,607 | 1.13% | 1,160 | 1 | City |
Bellingham is the largest city in Whatcom County, with a population of 96,857.
Sumas is the smallest city in Whatcom County, with a population of 1,702.
There are 7 cities in Whatcom County, Washington.