Western Conference (USL Championship)

;[5] Saint Louis FC and the Swope Park Rangers moved out to the Eastern Conference; Seattle Sounders FC 2 rebranded as Tacoma Defiance.

Changes from 2019: San Diego Loyal SC was added as an expansion franchise; the Tulsa Roughnecks were renamed FC Tulsa; Fresno FC was disbanded.

[6] Changes from 2020: The conference was divided into two divisions, Mountain and Pacific; Oakland Roots SC joined in from NISA: the Portland Timbers 2 was withdrawn by the MLS parent club; Reno 1868 FC was disbanded; Oklahoma City Energy and FC Tulsa moved out to the Eastern Conference.

[7] Changes from 2021: The Mountain and Pacific divisions were dropped; Monterey Bay FC was added as an expansion franchise; the Real Monarchs and the Tacoma Defiance were withdrawn by their MLS parent clubs and moved to MLS Next Pro; Austin Bold FC went on hiatus; will move to a yet-to-be-named Texas city for the 2023 season.

[8] Changes from 2022: The LA Galaxy II was withdrawn by their MLS parent club and moved to MLS Next Pro;[9] Changes from 2023: Rio Grande Valley FC Toros[10] and San Diego Loyal SC[11] folded.