| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Sibagna (historical) | city | California | United States | 34.10 | -118.11 | 400 | |
| Siberia | city | California | United States | 34.63 | -115.99 | 1233 | |
| Sibley (historical) | city | California | United States | 37.98 | -121.16 | 59 | |
| Sicard Flat | city | California | United States | 39.23 | -121.35 | 360 | |
| Sides (historical) | city | California | United States | 36.25 | -119.10 | 367 | |
| Sids Place | city | California | United States | 40.42 | -123.46 | 3503 | |
| Sierra Brooks | city | California | United States | 39.64 | -120.22 | 5236 | |
| Sierra Cedars | city | California | United States | 37.08 | -119.31 | 5869 | |
| Sierra City | city | California | United States | 39.57 | -120.63 | 4356 | |
| Sierra Glen | city | California | United States | 36.64 | -119.00 | 3349 | |
| Sierra Heights | city | California | United States | 36.19 | -119.06 | 830 | |
| Sierra Heights | city | California | United States | 34.17 | -117.44 | 1791 | |
| Sierra Knoll Estates | city | California | United States | 39.07 | -121.03 | 1860 | |
| Sierra Madre | city | California | United States | 34.16 | -118.05 | 830 | |
| Sierra Pines | city | California | United States | 39.53 | -120.01 | 5029 | |
| Sierra Sky Park | city | California | United States | 36.84 | -119.87 | 298 | |
| Sierra Springs | city | California | United States | 38.71 | -120.61 | 3398 | |
| Sierra Trailer Park | city | California | United States | 37.36 | -118.40 | 4199 | |
| Sierra Villa Mobile Home Park | city | California | United States | 34.75 | -118.13 | 2509 | |
| Sierra Village | city | California | United States | 38.07 | -120.17 | 4583 | |
| Sierra Vista | city | California | United States | 37.15 | -120.29 | 239 | |
| Sierra Vista | city | California | United States | 34.10 | -118.16 | 830 | |
| Sierra Vista Mobile Estates | city | California | United States | 36.34 | -119.63 | 226 | |
| Sierra Vista Park | city | California | United States | 39.23 | -121.08 | 2598 | |
| Sierra Vista Trailer Park | city | California | United States | 33.22 | -117.25 | 396 | |
| Sierraville | city | California | United States | 39.59 | -120.37 | 5029 | |
| Signal Butte | city | California | United States | 41.28 | -122.19 | 4225 | |
| Signal Hill | city | California | United States | 33.80 | -118.17 | 150 | |
| Signal Port (historical) | city | California | United States | 38.83 | -123.62 | 0 | |
| Silangang Palo Alto | city | California | United States | 37.47 | -122.14 | 45 | |
| Silongkoyo (historical) | city | California | United States | 39.94 | -120.95 | 4189 | |
| Silt | city | California | United States | 35.00 | -117.75 | 2509 | |
| Silvas Grove (historical) | city | California | United States | 38.60 | -121.54 | 16 | |
| Silver City | city | California | United States | 36.47 | -118.65 | 6709 | |
| Silver Creek (historical) | city | California | United States | 39.94 | -121.07 | 4189 | |
| Silver Dons Mobile Home Park | city | California | United States | 33.24 | -116.37 | 830 | |
| Silver Lake Heights | city | California | United States | 34.10 | -118.26 | 830 | |
| Silver Lakes | city | California | United States | 34.75 | -117.34 | 2509 | |
| Silver Mountain (historical) | city | California | United States | 38.61 | -119.77 | 6709 | |
| Silver Penny Mobile Home Park | city | California | United States | 37.51 | -122.25 | 22 | |
| Silver Spur Mobile Manor | city | California | United States | 33.69 | -116.41 | 889 | |
| Silver Strand | city | California | United States | 34.15 | -119.22 | 0 | |
| Silver Terrace | city | California | United States | 37.73 | -122.40 | 173 | |
| Silverado | city | California | United States | 33.75 | -117.64 | 1669 | |
| Silverthorn | city | California | United States | 40.65 | -122.39 | 830 | |
| Simerson | city | California | United States | 39.42 | -123.36 | 1669 | |
| Simi | city | California | United States | 38.64 | -122.87 | 196 | |
| Simi Valley | city | California | United States | 34.27 | -118.78 | 830 | |
| Simmler | city | California | United States | 35.35 | -119.99 | 2053 | |
| Simms | city | California | United States | 37.80 | -121.10 | 72 | |
| Simons | city | California | United States | 33.99 | -118.13 | 164 | |
| Sims | city | California | United States | 41.07 | -122.36 | 1801 | |
| Singing Springs | city | California | United States | 34.32 | -118.13 | 3599 | |
| Sisquoc | city | California | United States | 34.86 | -120.29 | 830 | |
| Sites | city | California | United States | 39.31 | -122.34 | 383 |