| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Farmington | 1 | 45,968 | 46,501 | -0.19% | 1,334 | 34 | City |
| Bloomfield | 2 | 7,319 | 7,411 | -0.22% | 395 | 19 | City |
| Aztec | 3 | 6,070 | 6,192 | -0.34% | 356 | 17 | City |
| Kirtland | 4 | 569 | 582 | -0.52% | 330 | 2 | Town |
Farmington is the largest city in San Juan County, with a population of 45,968.
Kirtland is the smallest city in San Juan County, with a population of 569.
There are 4 cities in San Juan County, New Mexico.