- Shell Rock
- Shellsburg
- Shueyville
- Sibley
- Sigourney
- Sioux Center
- Sioux City
- Sioux Rapids
- Soldier
- South English
- Spillville
- Spragueville
- Springbrook
- State Center
- Steamboat Rock
- Sciola
- Storm Lake
- Story City
- Strawberry Point
- Struble
- Sully
- Swaledale
- Swan
- Swea City
- Swisher
- Spring Valley
- Sunrise Mobile Home Park
- South Towne Park
- Summit
- Sweetland Center