Major League Soccer and United Soccer League entered the sixth season of their partnership in 2018. The 2018 USL regular season begins on Friday, with 33 teams participating this season. Louisville City FC enter as the defending USL Cup champion.
Along the terms of the partnership, MLS teams can enter affiliation agreements with independently-owned USL teams, can enter larger hybrid affiliate partnerships with USL teams, or own and operate their own USL teams. MLS teams can loan out players to their USL teams or affiliates, but they can also loan out players to other USL teams if they choose.
Here is a complete list of MLS-owned and MLS-affiliated USL teams for the 2018 season, as of March 15:
- Atlanta United FC - Atlanta United 2
- Chicago Fire - Tulsa Roughnecks FC (affiliate)
- Colorado Rapids - Charlotte Independence (affiliate)
- Columbus Crew SC - No formal affiliation, will continue to find loan opportunities for players
- D.C. United - Richmond Kickers (affiliate)
- FC Dallas - Oklahoma City Energy FC (affiliate)
- Houston Dynamo - Rio Grande Valley FC (hybrid affiliate)
- LAFC - Orange County SC (affiliate)
- LA Galaxy - LA Galaxy II
- Minnesota United FC - No formal affiliation
- Montreal Impact - Ottawa Fury FC (affiliate)
- New England Revolution - No formal affiliation
- New York City FC - San Antonio FC (affiliate)
- New York Red Bulls - New York Red Bulls II
- Orlando City - No USL affiliate in 2018
- Philadelphia Union - Bethlehem Steel FC (affiliate)
- Portland Timbers - Portland Timbers 2
- Real Salt Lake - Real Monarchs SLC
- San Jose Earthquakes - Reno 1868 FC (hybrid affiliate)
- Seattle Sounders FC - Seattle Sounders FC 2
- Sporting Kansas City - Swope Park Rangers
- Toronto FC - Toronto FC II
- Vancouver Whitecaps FC - Fresno FC (affiliate)
