Sak
- Sabine River - Texas, Louisiana
- Sac River - Missouri
- Sacagawea River - Montana
- Sacandaga River - New York
- Saco River - New Hampshire, Maine
- Sacramento River - California
- Saddle River - New York, New Jersey
- Sagavanirktok River - Alaska
- Saginaw River - Michigan
- Skug River - Massachusetts
- St. Clair River - Michigan
- St. Croix River - Maine
- St. Croix River - Wisconsin, Minnesota
- St. Francis River - Maine
- St. Francis River - Minnesota
- St. Francis River - Missouri, Arkansas
- St. Joe River - Idaho
- St. John River - Maine
- St. Johns River - Florida
- St. Jones River - Delaware
- St. Joseph River (Lake Michigan) - Michigan, Indiana
- St. Joseph River (Maumee River) - Michigan, Ohio, Indiana
- St. Lawrence River - New York
- St. Louis River - Minnesota, Wisconsin
- St. Lucie River - Florida
- St. Maries River - Idaho
- St. Marks River - Florida
- St. Martin River - Maryland
- St. Mary River - Montana
- St. Marys River - Florida, Georgia
- St. Marys River - Indiana, Ohio
- St. Marys River - Maryland
- St. Marys River - Michigan
- St. Regis River - Montana
- St. Regis River - New York
- St. Vrain Creek or St. Vrain River - Colorado
- Sakonnet River - Rhode Island
Read more about this topic: List Of Rivers Of The United States: S, Sab