On October 14, 2014, Seattle Sounders FC announced the creation of a development team named Seattle Sounders FC 2, to join the USL PRO in 2015, while also unveiling the team logo. The concept behind the logo was that players in the development squad would "earn the crest" when they progressed on to the MLS first team.
| Eastern Conference:|
Bethlehem Steel FC | Charleston Battery | Charlotte Independence | FC Cincinnati | Harrisburg City Islanders | Louisville City FC | New York Red Bulls II | Orlando City B | Ottawa Fury FC | Pittsburgh Riverhounds | Richmond Kickers | Rochester Rhinos | St. Louis FC | Tampa Bay Rowdies | Toronto FC II
Clubs on hiatus: