The league is owned and operated by United Soccer Leagues (USL) and was formed as result of the organization's merger of the old USL First and Second Divisions, following the controversial 2010 season which saw neither the USL First Division nor the North American Soccer League (NASL) receive sanctioning from the USSF, resulting in the temporary USSF Division 2 Pro League. The merger is meant to consolidate USL's position within the American professional soccer landscape and focus on stability, commercial growth and the professional development of soccer in four main regions throughout the United States and Canada.
In January 2013, USL and MLS reached an agreement to integrate USL Pro league competition with the MLS Reserve League, primarily to improve player development in North America, strengthen league competition and build ties between divisions in the American soccer pyramid. This multi-year deal encourages MLS and USL Pro team affiliations and player loans, and it will lead to more games for teams and developing players.
USL Pro's scheduling format has changed for the 2015 season to accommodate the expansion that took place during the 2014-2015 off-season, and the league's resulting need to divide teams into conferences — which has eliminated the single table.
All teams will play 28 regular-season matches stretching from March to September. This will include a 22-game, double-round-robin schedule that will pit each team against all its conference opponents at home and on the road. The remaining six fixtures will be played against regional rivals, which will lead to some inter-conference regular season matches. The top six finishers in each conference will go through to the October playoffs, which will continue to be a series of single-game knockout rounds. After three rounds of intra-conference play, the two conference champions will meet in the championship match, to be hosted by the team with the better regular-season record.
On September 8, 2010, the United Soccer Leagues formally announced the creation of USL Pro in a press release. Prior to the official announcement of the new league, on August 11, 2010, the Dayton Dutch Lions FC revealed they would be joining the "USL-Pro Championship Division (former USL-2)" at a press conference, revealing the name of the new league before its official announcement. With this disclosure, the Dutch Lions were the first confirmed team in USL Pro for its inaugural 2011 season. Alongside the announcement of the new league, the Richmond Kickers revealed they would be moving to USL Pro for 2011. With the departure of the Portland Timbers to MLS in 2011 and the defection of the Puerto Rico Islanders to the NASL from the USL First Division, the Austin Aztex were the lone First Division team left to fold into USL Pro.
On September 22, 2010, the "Caribbean Division" of USL Pro was announced, with teams from Puerto Rico and Antigua and Barbuda signing on to compete in the league. With the addition of Puerto Rico United to the league and "Caribbean Division", league representatives expressed their intent to see expansion in the region continue, with an eventual 8-team "Caribbean Conference". With the inclusion of a team from Los Angeles, this division eventually became the International Division. On September 22, 2010, USL announced that Sevilla FC Puerto Rico and River Plate Puerto Rico would be joining USL Pro in 2011 alongside Antigua Barracuda FC as part of the building blocks of a Caribbean division. On September 28, 2010, USL announced that one of their flagship clubs and reigning 2010 USL Second Division Champions, the Charleston Battery, would be joining USL Pro for its launch in 2011. On September 30, 2010, nearly two months following the team's own announcement of a "USL Pro Championship Division" move, the USL formally announced Dayton Dutch Lions FC would join USL Pro. On October 4 and 7, 2010, the USL revealed two Second Division clubs, the Charlotte Eagles and the Harrisburg City Islanders, would be making the jump to USL Pro for 2011.
On November 9, 2010, former USL-2 Division side Wilmington Hammerheads officially joined the league as the 12th team, followed on November 17, 2010 by F.C. New York. The expected number of teams to launch league play in 2011 was announced as 18–20, alongside the announcement of the Wilmington Hammerheads joining the league.
The Los Angeles Blues, associated with the successful women's Pali Blues organization, were added on December 7, 2010 with a message of future "Western Conference" growth into 2012. The "Caribbean Division" of USL Pro grew to four teams on December 9, 2010 with the addition of Puerto Rico United to the league, marking the last of the 15 teams that would compete in USL Pro in its inaugural 2011 season.
On September 14, 2010, USL President Tim Holt expressed the desired structure for the league to launch with 14–18 teams across 4 specific geographic areas in 2011, expansion to 22–26 teams by 2013, and 28–32 teams by 2015.
Following USL Pro's first annual general meeting, the league confirmed it would debut with 16 teams playing a 24-game regular season schedule in 2011, with planned growth for 20–24 teams to start the 2012 season.
USL Pro debuted in 2011, starting with 15 teams playing a 24-game regular season schedule. American and National Division teams played a home-and-away series against all opponents from the two divisions (totaling 18 games), 2 additional regional rivalry matches, with each team making an additional trip to either Los Angeles or the Caribbean to play two games while hosting International Division competition for two games. International Division teams played each team in their division four times (twice home, twice away, totaling 16 games) while traveling to face American or National Division opponents in four games and hosting those opponents for four games.
The original playoff format saw eight teams compete in a one-game quarterfinal. Both the American and National Divisions saw their top three teams advance for an inter-divisional playoff, while the top 2 teams in the International Division played-off against each other to reach the semifinals. The four remaining teams were re-seeded for a single semi-final match, again with the higher seed hosting, leading up to a single match for the USL Pro Championship. In all playoff matches the highest seeded team hosted.
On May 10, 2011, early in the league's inaugural season, the USL announced that it was dropping the three Puerto Rican clubs from the USL PRO schedule. The PRSL clubs were dropped due to economic and ownership issues. The two remaining International Division teams – Antigua Barracuda FC and Los Angeles Blues – were re-aligned into the American and National Divisions. Due to the removal of the International Division, the revised playoff format featured the top four teams in each of the two divisions. The two division playoff winners met in the USL Pro Championship at the home venue of the team with the better record.
Following the 2011 season, USL Pro announced with the release of the 2012 season schedule that F.C. New York would not be returning to play, with the former National and American Divisions being dissolved to form a single, eleven team league table. With F.C. New York withdrawing in January 2012, the league announced an eleven team single-table schedule for the 2012 season.
On January 23, 2013 USL Pro and MLS announced a multi-year agreement to integrate MLS Reserve League play with USL Pro teams, first through team affiliations and "interleague" play, but eventually fully merging MLS Reserves into the USL Pro structure. The stated goals of this partnership are to improve North American player development, strengthen league competition, build long-term ties between the leagues and expand the audience for both the leagues and developing players.
In what would become a major trend, on January 29, 2014, the LA Galaxy announced the creation of LA Galaxy II, a reserve team within the club's existing development structure. The Galaxy purchased a USL Pro expansion franchise and became the first MLS club to enter its reserve team into the USL Pro.
Expansion of MLS partnership and rebranding (2015–)
USL Pro nearly doubled the number of teams in the league for 2015 in large part due to MLS franchises following the path taken by the LA Galaxy II. Seven MLS clubs announced the purchase of a USL Pro franchise for their reserve team. These MLS franchises joined 4 independent expansion teams that were previously announced for Colorado Springs, St. Louis, Tulsa and Austin. Additionally, Orlando City sold its franchise rights to Louisville interests, which unveiled Louisville City FC on June 3, 2014 as an affiliate of the new MLS side, and the USL announced that the Charlotte Eagles would drop to the Premier Development League (PDL) while selling their franchise rights to another Charlotte group which formed the Charlotte Independence for play beginning in 2015. Finally, on December 11, 2014, the Dayton Dutch Lions self-relegated to play in the PDL starting in 2015.
MLS affiliations were announced for the remaining MLS teams that did not have an affiliation in 2014 and did not elect to purchase a USL Pro franchise. On September 18, 2014 the Colorado Rapids announced an affiliation partnership with the Charlotte Independence. On January 16, 2015 New York City FC announced that it would have an affiliate relationship with the Wilmington Hammerheads and the Chicago Fire announced their affiliation with St Louis. On February 9, 2015, FC Dallas announced it would add Arizona United SC as its USL Pro affiliate. As a result, all 20 MLS teams for the 2015 season were either fielding their own team in the USL Pro or were affiliated with an independent USL Pro club.
The USL also announced in 2015 that the league would be divided into two conferences. Teams would play a 28-game schedule with 22 games against all the teams in their conference, and the teams would be further assigned to four-club subdivisions for the other six games with an eye towards geographic rivalries between clubs.
On February 10, 2015, the league announced a branding change, with the league now called the "United Soccer League" or "USL" for short. They introduced a new logo and branding, and stated their intention to re-apply for Division II status within the United States Soccer Federation hierarchy.
On July 15, 2015, USL announced that the 25th franchise in the league was awarded to Lone Star, LLC and the team would be named Rio Grande Valley FC. Alec Papadakis, USL President stated that the club already had a "10,000-seat soccer-specific stadium" under construction. In a first for the USL, the team will have a "hybrid" affiliation with the Houston Dynamo who would be responsible for the tactical part of the club, while the ownership group, Lone Star, would be responsible for operations and management.
The Austin Aztex announced that they would go on hiatus for the 2016 USL season on October 2, 2015. Floods damaging House Park midway through the 2015 season forced the team to relocate to a high school facility. The team will return in 2017, pending construction of a new, soccer-specific stadium.
In a telephone interview on July 23, 2015, USL President Jake Edwards indicated that although the teams have not been announced, the league has decided which teams will start in 2016, "The deals are done and the plans are finalized." In addition to Rio Grande Valley FC and FC Cincinnati, Cincinnati mayor John Cranley stated that the USL now has 29 teams. News reports indicate the additional teams that are likely to be added .
News reports also suggest that USL is already planning additional teams for 2017.
FC Dallas: In August 2014, management stated they intend to have a USL team for the 2016 season; however, there has been no further news regarding their intentions and they have been left off news reports regarding the 2016 USL season.
Nashville FC: On July 29, 2015, MLSSoccer.com reported that FC Nashville club president Chris Jones is exploring a move to USL or NASL. If successful this would be the first supporters owned club in either league.
Sacramento Republic played before a record crowd of 20,231 in its home debut on April 26, 2014 at Hughes Stadium. This broke the USL Pro's previous record for attendance at a regular-season match of 10,687, set by Orlando City at the Citrus Bowl on August 11, 2013.
^Originally, the Monarchs planned to play at the Utah State Fairpark; however, the State of Utah did not extend the lease on the Fairgrounds, a requirement for the downtown stadium. So Del Loy Hansen announced plans to build a stadium in West Valley City in February 2015.