21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Yreka | 1 | 7,816 | 7,795 | 0.05% | 783 | 9.98 | City |
| Lake Shastina | 2 | 3,760 | 2,790 | 7.15% | 937 | 4.01 | CDP |
| Mount Shasta | 3 | 3,152 | 3,219 | -0.41% | 836 | 3.77 | City |
| Weed | 4 | 2,386 | 2,856 | -3.79% | 495 | 4.82 | City |
| Dunsmuir | 5 | 1,602 | 1,702 | -1.23% | 999 | 1.60 | City |
| Montague | 6 | 1,156 | 1,221 | -1.11% | 650 | 1.78 | City |
| McCloud | 7 | 923 | 899 | -1.28% | 381 | 2.42 | CDP |
| Tulelake | 8 | 845 | 900 | -1.29% | 2,061 | 0.41 | City |
| Dorris | 9 | 812 | 861 | -1.22% | 1,157 | 0.70 | City |
| Fort Jones | 10 | 657 | 697 | -1.2% | 1,091 | 0.60 | City |
| Etna | 11 | 637 | 676 | -1.24% | 832 | 0.77 | City |
| Happy Camp | 12 | 551 | 861 | -7.24% | 46 | 12.11 | CDP |
| Hornbrook | 13 | 414 | 243 | 2.73% | 354 | 1.17 | CDP |
| Grenada | 14 | 196 | 295 | -5.31% | 379 | 0.52 | CDP |
| Gazelle | 15 | 154 | 111 | 6.94% | 229 | 0.67 | CDP |
| Macdoel | 16 | 146 | 26 | 0.69% | 874 | 0.17 | CDP |
| Mount Hebron | 17 | 141 | 61 | 6.82% | 188 | 0.75 | CDP |
| Tennant | 18 | 100 | 21 | 7.53% | 295 | 0.34 | CDP |
| Greenview | 19 | 67 | 139 | -11.84% | 52 | 1.29 | CDP |
| Edgewood | 20 | 58 | 39 | 7.41% | 57 | 1.03 | CDP |
| Carrick | 21 | 43 | 58 | -12.24% | 729 | 0.06 | CDP |
Yreka is the largest city in Siskiyou County, with a population of 7,816.
Carrick is the smallest city in Siskiyou County.
There are 21 cities in Siskiyou County, California.