| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Siam | city | Iowa | United States | 40.63 | -94.89 | 1151 | |
| Sibley | city | Iowa | United States | 43.40 | -95.75 | 1669 | |
| Sibyl (historical) | city | Iowa | United States | 41.95 | -90.19 | 830 | |
| Sidney | city | Iowa | United States | 40.75 | -95.65 | 1151 | |
| Sigourney | city | Iowa | United States | 41.33 | -92.20 | 830 | |
| Silver City | city | Iowa | United States | 41.11 | -95.64 | 1040 | |
| Silver Creek Mobile Home Community | city | Iowa | United States | 41.57 | -90.62 | 830 | |
| Silver Lake | city | Iowa | United States | 43.48 | -93.37 | 1669 | |
| Sinclair | city | Iowa | United States | 42.50 | -92.73 | 1046 | |
| Sioux Center | city | Iowa | United States | 43.08 | -96.18 | 1669 | |
| Sioux City | city | Iowa | United States | 42.50 | -96.40 | 1125 | |
| Sioux Rapids | city | Iowa | United States | 42.89 | -95.15 | 1669 | |
| Sixmile | city | Iowa | United States | 41.91 | -90.30 | 830 | |
| Sixteen | city | Iowa | United States | 43.13 | -91.32 | 898 |