| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Sieler | city | Washington | United States | 47.07 | -119.18 | 1200 | |
| Sietl | city | Washington | United States | 47.61 | -122.33 | 196 | |
| Sietlas | city | Washington | United States | 47.61 | -122.33 | 196 | |
| Sifton | city | Washington | United States | 45.67 | -122.53 | 203 | |
| Sightly | city | Washington | United States | 46.30 | -122.71 | 830 | |
| Silcott | city | Washington | United States | 46.42 | -117.20 | 830 | |
| Siler | city | Washington | United States | 46.51 | -121.93 | 849 | |
| Silvana | city | Washington | United States | 48.20 | -122.25 | 55 | |
| Silvana Terraces | city | Washington | United States | 48.20 | -122.28 | 190 | |
| Silver Beach | city | Washington | United States | 48.77 | -122.41 | 308 | |
| Silver Beach | city | Washington | United States | 46.64 | -121.24 | 2798 | |
| Silver Brook | city | Washington | United States | 46.54 | -121.91 | 902 | |
| Silver Creek | city | Washington | United States | 46.53 | -122.59 | 830 | |
| Silver Creek Meadows Mobile Home Park | city | Washington | United States | 47.65 | -122.66 | 190 | |
| Silver Firs | city | Washington | United States | 47.87 | -122.16 | 830 | |
| Silver Lake | city | Washington | United States | 47.55 | -117.65 | 2509 | |
| Silver Lake | city | Washington | United States | 46.30 | -122.81 | 830 | |
| Silver Shores Senior Mobile Home Park | city | Washington | United States | 47.89 | -122.22 | 413 | |
| Silvercrest Mobile Home Park | city | Washington | United States | 47.04 | -122.38 | 830 | |
| Silverdale | city | Washington | United States | 47.64 | -122.69 | 0 | |
| Silverdale Mobile Estates | city | Washington | United States | 47.62 | -122.65 | 209 | |
| Silverton | city | Washington | United States | 48.08 | -121.57 | 1968 | |
| Similk Beach | city | Washington | United States | 48.45 | -122.58 | 0 | |
| Sims Corner | city | Washington | United States | 47.82 | -119.36 | 2509 | |
| Sine | city | Washington | United States | 47.03 | -123.26 | 396 | |
| Sisco | city | Washington | United States | 48.13 | -122.14 | 216 | |
| Sisco Heights | city | Washington | United States | 48.12 | -122.10 | 830 | |
| Sixprong | city | Washington | United States | 45.86 | -120.03 | 869 | |
| Siyaatil | city | Washington | United States | 47.61 | -122.33 | 196 |