The USL Championship (USLC), is a professional men's soccer league in the United States that began its inaugural season in 2011. The USL is sanctioned by the United States Soccer Federation (U.S. Soccer) as a Division II Professional League since 2017, placing it under Major League Soccer (Division I) in the hierarchy. The USL is headquartered in Tampa, Florida. The league is owned and operated by United Soccer League (originally "United Soccer Leagues") and was formed as result of the merger of their USL First (USL-1) and Second Divisions (USL-2), following the controversial 2010 season which saw neither the USL-1 nor the North American Soccer League (NASL) receive Division II sanctioning from the USSF, resulting in the temporary USSF Division 2 Pro League. United Soccer Leagues stated that the merger would strengthen the league's position within the American professional soccer landscape through stability, commercial growth and the professional development of soccer in four main regions throughout the United States and Canada. Formerly known as United Soccer League (USL) and USL Pro, in January 2013, United Soccer Leagues and MLS reached an agreement to integrate the USL league competition with the MLS Reserve League, primarily to improve player development in North America, strengthen league competition and build ties between leagues in the American soccer pyramid. This multi-year deal encourages MLS and USL team affiliations and player loans, aiming to have more games for teams and developing players. As of the 2020 season, 14 USL Championship teams are affiliated to MLS teams. Most teams have an affiliate in either the USL Championship or third-level USL League One (USL1), but Columbus Crew SC, FC Cincinnati, Los Angeles FC, Montreal Impact, Nashville SC, and Vancouver Whitecaps FC have no affiliated team in these leagues.