| Sinclair, ND (Township) |
| Sinclair, WY (Town) |
| Sinclair, MN (Township) |
| Sinclairville, NY (Village) |
| Sinking Spring, PA (Borough) |
| Sinking Spring, OH (Village) |
| Sinnott, MN (Township) |
| Sinton, TX (City) |
| Sioux, ND (Township) |
| Sioux Agency, MN (Township) |
| Sioux Center, IA (City) |
| Sioux City, IA (City) |
| Sioux County, ND (County) |
| Sioux County, IA (County) |
| Sioux County, NE (County) |
