San Diego FC

San Diego's earliest professional soccer team was the short-lived San Diego Toros, a North American Soccer League (NASL) team that relocated from Los Angeles in 1968 and played a single season. A second NASL team, the San Diego Jaws, was established in 1976 from the former Baltimore Comets and played one year before moving to Las Vegas; the club returned in 1978 and was renamed the Sockers, playing outdoor matches at Jack Murphy Stadium, which was shared with the National Football League's San Diego Chargers and Major League Baseball's San Diego Padres. The Sockers had poor attendance but survived the folding of the NASL by moving to the Major Indoor Soccer League, where they won eight championships in nine seasons. The team moved to the Continental Indoor Soccer League in 1993 and folded in 1997; the name was later revived for a second indoor team from 2001 to 2004 and a third indoor team that began play in 2009. Other outdoor teams, including the San Diego Flash and San Diego 1904 FC, had played short stints in the lower divisions of American soccer in the 2000s and 2010s before folding.

During the formation of MLS in the mid-1990s, San Diego was not among the U.S. cities to formally submit a bid for a team in the inaugural season, but expressed interest and held several meetings with the league. MLS commissioner Doug Logan described San Diego as a "prime candidate" for an expansion team, but the city's lack of a suitable stadium to accommodate soccer was a "major hurdle"; at the time, Jack Murphy Stadium was shared with the Padres and had a larger capacity than the league's desired size. The renovated Jack Murphy Stadium (renamed to Qualcomm Stadium) hosted several exhibition matches as well as the 1999 MLS All-Star Game, which drew an attendance of 23,277; it was the only MLS All-Star Game to be played outside of an active or future MLS market.

Following the approval of plans to build a downtown ballpark for the Padres, the MLS expansion committee voiced their support of a potential team playing at Qualcomm Stadium—either permanently or until a soccer-specific stadium was built. The San Diego market was considered for Chivas USA, an MLS expansion team that later served as a reserve team for C.D. Guadalajara of the Mexican Primera División. The team instead chose to share its home venue with the LA Galaxy in Carson, California, and played for ten seasons before folding for low attendance and ownership issues. The league continued to list San Diego as a potential candidate for expansion and negotiated with several interested investor groups, but the lack of a suitable stadium prevented further consideration. Balboa Stadium, the 1960s home of the Chargers and Jaws, was also mentioned as a potential site for a smaller stadium built for an MLS team.

A new team across the Mexican border, Club Tijuana (nicknamed the Xolos), was founded in 2007 and promoted to Liga MX—Mexico's top-flight league—in 2011. The team attracted support from fans in San Diego—about 20 miles (32 km) north of their home stadium—and played several exhibition matches in the area at various venues, including Qualcomm Stadium and the Padres' Petco Park. San Diego also remained one of the top U.S. viewing markets for television broadcasts of the FIFA World Cup, Premier League, and other overseas soccer competitions. The area had also produced several prominent players for the United States men's and women's national teams.

The San Diego Chargers announced plans to relocate to the Los Angeles area in 2015 while it also pursued a new downtown San Diego stadium, which required voter approval but was rejected. The team's departure was made official in early 2017 and opened an opportunity for a new MLS expansion bid to be led by businessman Mike Stone with several other investors, including Padres owner Peter Seidler and former soccer player Landon Donovan. A separate bid from former Padres owner John Moores—who had shown interest in an MLS team in the 1990s—and an unspecified Premier League team was withdrawn a year earlier. The Stone bid proposed a redevelopment of the Qualcomm Stadium site named "SoccerCity" that would include mixed-use development and a park surrounding a stadium shared with San Diego State University (SDSU)'s athletic teams, known as the Aztecs. The stadium would seat 20,000 to 32,000 spectators and cost $200 million to construct. A separate proposal from SDSU, named SDSU West, was announced and placed on the same November 2018 ballot; SoccerCity was defeated with 30 percent of votes, while SDSU West earned 55 percent approval.

A second-division team, San Diego Loyal SC, was established by Warren Smith and Landon Donovan in 2019 and began play the following year in the USL Championship at Torero Stadium. The team also showed interest in launching an MLS expansion with other partners, but were not part of any later bids. The SDSU West stadium, named Snapdragon Stadium, opened in 2022 and became the home of San Diego Wave FC, a National Women's Soccer League expansion team that moved from Torero Stadium. The team set several U.S. women's soccer attendance records in their first season and drew 32,000 fans at the new Snapdragon Stadium. Several investor groups also approached SDSU to launch a MLS expansion team that would play at Snapdragon Stadium with financial concessions requested by the league. A separate proposal to build a mixed-use residential and hotel district in the suburb of Chula Vista with a soccer-specific stadium was announced in April 2023 by Petra Development Group and outside investors.

The Sycuan Band of the Kumeyaay Nation, a federally recognized Native American tribe and operators of local entertainment venues, began looking for opportunities to invest in sports ownership in December 2020. The tribe partnered with developer Brad Termini to bid for an MLS expansion team the following year and searched for a major financial partner with help from the league. The Sycuan Tribe contacted the Mansour Group, led by businessman Mohamed Mansour, who joined the bid in late 2022. In October 2022, The San Diego Union-Tribune reported that the proposed team would require an agreement with SDSU to use Snapdragon Stadium. San Diego competed with proposals from Las Vegas, who had previously been described as the "favorite" to become the 30th MLS team; the primary Las Vegas bid, led by Wes Edens and Nassef Sawiris, who co-owned Aston Villa F.C. in the Premier League, included a conceptual indoor stadium.

On May 18, 2023, at a Snapdragon Stadium event, MLS announced that the expansion team had been awarded to San Diego and would be owned by Mansour and the Sycuan Tribe. The ownership group paid a $500 million expansion fee according to media reports. Within a day, a total of 5,000 season ticket deposits had been sold. The team's name, San Diego Football Club, and colors were unveiled at an event on October 20. San Diego FC is scheduled to begin play in 2025, giving the state of California four clubs in MLS. The team's first player, former Loyal SC goalkeeper Duran Ferree, was signed in December 2023 and loaned to Orange County SC for the 2024 season.

San Diego FC announced a five-year partnership with Club Tijuana in May 2024 that will include an annual friendly match between the two teams, hosted in San Diego. It is the first partnership of its kind between individual MLS and Liga MX clubs. The team signed their first Designated Player, Mexico international and forward Hirving "Chucky" Lozano from PSV Eindhoven, to a four-year contract in June. Lozano will remain with PSV until the first San Diego FC training camp in January 2025. San Diego FC selected five players during the 2024 MLS expansion draft, which took place at the Mission Valley shopping mall on December 11. Three of the players were retained by the club, while two selections were traded to other MLS teams.

The team's first match will be played on February 23, 2025, at Dignity Health Sports Park against the defending MLS Cup champions LA Galaxy. The first home match for San Diego FC at Snapdragon Stadium is scheduled for March 1 against St. Louis City SC.