Si
- Siletz River - Oregon
- Siltcoos River - Oregon
- Silver Creek - Arizona
- Silver Creek - Indiana
- Silver Creek - Kentucky
- Silvies River - Oregon
- Similkameen River - Washington
- Simms Stream - New Hampshire
- Simons River - Delaware
- Simpson Creek - West Virginia
- Sinsinawa River - Wisconsin, Illinois
- Sioux River - Wisconsin
- Sippican River - Massachusetts
- Sipsey River - Alabama
- Sipsey Fork of the Black Warrior River - Alabama
- Siskiwit River - Wisconsin
- Sisquoc River - California
- Siuslaw River - Oregon
- Six Mile Creek - Alaska
- Six Run Creek - North Carolina
- Sixes River - Oregon
- Sixteen Mile Creek - Montana
Read more about this topic: List Of Rivers Of The United States: S