7 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bellingham | 1 | 97,855 | 91,870 | 1.03% | 3,470 | 28 | City |
| Ferndale | 2 | 17,486 | 15,146 | 2.28% | 2,428 | 7 | City |
| Lynden | 3 | 17,271 | 15,806 | 1.43% | 3,178 | 5 | City |
| Blaine | 4 | 6,606 | 5,901 | 1.82% | 1,183 | 6 | City |
| Everson | 5 | 3,278 | 2,950 | 1.71% | 2,196 | 1 | City |
| Nooksack | 6 | 1,763 | 1,499 | 2.56% | 1,918 | 1 | City |
| Sumas | 7 | 1,721 | 1,607 | 1.12% | 1,173 | 1 | City |
Bellingham is the largest city in Whatcom County, with a population of 97,855.
Sumas is the smallest city in Whatcom County, with a population of 1,721.
There are 7 cities in Whatcom County, Washington.