| Club | Based in | Founded | Home ground |
|---|---|---|---|
| Seacoast United Phantoms | Portsmouth | 2010 | Portsmouth High School |
| Shreveport Rafters FC | Shreveport | 2016 | Independence Stadium |
| Sioux Falls Thunder FC | — | 2016 | — |
| Sonoma County Sol | Santa Rosa | 2004 | Casa Grande High School |
| Southern California Fusion | Carlsbad | 2004 | — |
| Southern Oregon Fuego | — | 2009 | US Cellular Community Park |
| Sporting Arizona | Arizona | 1989 | — |
| Syracuse FC | Syracuse | 2017 | — |
| Temecula FC | Temecula | 2013 | Chaparral High School |
| Tucson Tiburons | Arizona | 2003 | Mountain View High School |
| Tyler FC | Tyler | 2016 | Brook Hill School |
| Utah Salt Ratz | Salt Lake City | 2003 | Rice–Eccles Stadium |
| West Texas FC | Midland | 2008 | Astound Broadband Stadium |
| Zanesville Athletic FC | — | 2012 | — |