Arizona League The league began play in 1988 as the Arizona League (AZL) on an experimental basis with four teams playing a 60-game schedule—the teams were affiliated with the
Milwaukee Brewers,
Oakland Athletics,
San Diego Padres, and a cooperative between the
Boston Red Sox and
Seattle Mariners. Games were scheduled in the morning in order to make sure the league did not compete with the
Phoenix Firebirds of the
Triple-A Pacific Coast League. The
Phoenix Diamondbacks debuted in 1996, the first affiliate of the
Arizona Diamondbacks to start playing professional baseball, two years before their parent club joined
Major League Baseball. A crowd of 6,124 attended the Diamondbacks' first game on June 25, 1996, a 15–7 loss to the
Phoenix Athletics. A number of local dignitaries were at the game, including
Buck Showalter and
Jerry Colangelo. The
Colorado Rockies started their rookie league team a year before starting major league play as well in 1992, sharing a team with the Cubs. The team, composed of the Rockies' first-ever draft picks, received a different level of notoriety than the Diamondbacks for their first rookie league game: as the players wore either Rockies jerseys or Cubs jerseys, the team did not have their uniform pants ready at the start of the season, and had to borrow pants from the Cubs. Between 1998 and 2000 an unaffiliated team composed of young players from the
Mexican League played out of the
Tucson Electric Park spring training complex, in part to add a fourth team to a southern division. Three
Tucson-based teams (the Mexican All-Stars, the Diamondbacks, and the Rockies) would leave the league after the 2000 season, largely due to travel concerns, followed by the White Sox two years later. All three teams later relocated their spring training complexes to the Phoenix metropolitan area, and the Diamondbacks and White Sox reinstated their rookie league teams. The start of the 2020 season was postponed due to the
COVID-19 pandemic before ultimately being cancelled on June 30.
Arizona Complex League Prior to the 2021 season, in continuation of MLB's reorganization of the minor leagues, the two US-based complex leagues were renamed, with the Arizona League becoming the Arizona Complex League (ACL). For 2025, the league consists of 17 teams. Beginning in 2024, the schedule was changed from a season which ran from late-June through late-August to a season which runs from early-May through late-July. This change also made it so the league would no longer feature players drafted in the current year's
draft, which in 2021 was changed to take place during the
All-Star Weekend in mid-July. ==Teams==