So
- Sol Duc River - Washington
- Soldier River - Iowa
- Somo River - Wisconsin
- Sonoita Creek - Arizona
- Sopchoppy River - Florida
- Soque River - Georgia
- Soucook River - New Hampshire
- Souhegan River - New Hampshire
- Souris River - North Dakota
- South River - Iowa
- South River - Maryland
- South River - New Hampshire, Maine
- South River - New Jersey, tributary of Great Egg Harbor River
- South River - New Jersey, Raritan River tributary
- South River - North Carolina, tributary of Black River
- South River - North Carolina, tributary of Neuse River
- South River - Virginia
- South Anna River - Virginia
- South Branch Ashuelot River - New Hampshire
- South Branch Baker River - New Hampshire
- South Branch Metedeconk River - New Jersey
- South Branch Pawtuxet River - Rhode Island
- South Branch Piscataquog River - New Hampshire
- South Branch Potomac River - Virginia, West Virginia
- South Branch Raritan River - New Jersey
- South Concho River - Texas
- South Fork Grand River - South Dakota
- South Fork Humboldt River - Nevada
- South Fork John Day River - Oregon
- South Fork Kentucky River - Kentucky
- South Fork Musselshell River - Montana
- South Fork New River - North Carolina
- South Fork Republican River - Colorado, Kansas, Nebraska
- South Fork Shenandoah River - Virginia
- South Fork Solomon River - Kansas
- South Fork South Branch Potomac River - West Virginia
- South Fork South Platte River - Colorado
- South Platte River - Colorado, Nebraska
- South Santiam River - Oregon
- South Umpqua River - Oregon
- South Yamhill River - Oregon
Read more about this topic: List Of Rivers Of The United States: S