Triple-A (officially Class AAA) is the highest level of play in Minor League Baseball in the United States since 1946. Currently, two leagues operate at the Triple-A level, Triple-A East and Triple-A West, with a total of 30 teams, 20 in the East and 10 in the West. Triple-A teams can be located both in smaller cities as well as larger metropolitan areas without Major League Baseball teams, such as Austin, Jacksonville, Columbus, and Charlotte.
All current Triple-A teams are located in the United States; before 2008, some Triple-A leagues also fielded teams in Canada, and from 1967 to 2020 the Mexican League was classified as Triple-A. Other than the current two Triple-A leagues, only five other leagues have ever held the classification.
Prior to 1946, the top level of Minor League Baseball was Double-A, which had been established in 1912. The Triple-A classification was created before the 1946 season, and began with all three leagues then in Double-A moving up to the new level:
This structure would persist for the next 75 years with only a few changes:
The IL, PCL, and Mexican League continued as Triple-A leagues until Major League Baseball (MLB) reorganized the minor leagues prior to the 2021 season. At that time, the IL and PCL were discontinued and replaced with Triple-A East and Triple-A West. The Mexican League continues to operate, independently.
While all current and the majority of past Triple-A teams have been located in the United States, Triple-A teams have also been based in:
Triple-A teams' main purpose is to prepare players for the Major Leagues. ESPN wrote in 2010:
Winning is nice, but secondary. It's much more important for a young prospect like outfielder Xavier Paul to get regular at-bats against lefties, or work on dropping down sacrifice bunts with a runner on first, than it is to take three of four from the Portland Beavers.
Both young players and veterans play for Triple-A teams:
There are the young prospects speeding through the organization on the fastest treadmill, the guys who used to be young prospects who are in danger of topping out in Triple-A, the 30-somethings trying to get back to the majors after an injury or a rough patch, and the guys just playing a few more seasons because someone still wants them and they still want to.
Most, if not all, of the players on an MLB team's expanded roster who are not currently on the team's active roster are assigned to the team's Triple-A club. Expanded rosters consist of 40 players, while active rosters generally consist of 26 players as of the 2021 season. Most Triple-A teams are based close to their MLB parent club, as activating a Triple-A player as an injury replacement is a common occurrence.
Teams at this level are divided into two leagues: Triple-A East and Triple-A West. The Triple-A East fields teams primarily in the Eastern United States, while the Triple-A West fields teams mostly in the Western United States. Each of the 30 Major League Baseball teams has an affiliation with one Triple-A team in the United States.
|Division||Team||Founded||MLB Affiliation||Affiliated Since||City||Stadium||Capacity|
|Midwest||Columbus Clippers||1977||Cleveland Indians||2009||Columbus, Ohio||Huntington Park||10,100|
|Indianapolis Indians||1902||Pittsburgh Pirates||2005||Indianapolis, Indiana||Victory Field||13,750|
|Iowa Cubs||1969||Chicago Cubs||1981||Des Moines, Iowa||Principal Park||11,500|
|Louisville Bats||1982||Cincinnati Reds||2000||Louisville, Kentucky||Louisville Slugger Field||13,131|
|Omaha Storm Chasers||1969||Kansas City Royals||1969||Papillion, Nebraska||Werner Park||9,023|
|St. Paul Saints||1993||Minnesota Twins||2021||Saint Paul, Minnesota||CHS Field||7,210|
|Toledo Mud Hens||1965||Detroit Tigers||1987||Toledo, Ohio||Fifth Third Field||10,300|
|Northeast||Buffalo Bisons||1979||Toronto Blue Jays||2013||Buffalo, New York||Sahlen Field||16,600|
|Lehigh Valley IronPigs||2008||Philadelphia Phillies||2007||Allentown, Pennsylvania||Coca-Cola Park||10,100|
|Rochester Red Wings||1899||Washington Nationals||2021||Rochester, New York||Frontier Field||10,840|
|Scranton/Wilkes-Barre RailRiders||1989||New York Yankees||2007||Moosic, Pennsylvania||PNC Field||10,000|
|Syracuse Mets||1934||New York Mets||2019||Syracuse, New York||NBT Bank Stadium||10,815|
|Worcester Red Sox||2021||Boston Red Sox||2021||Worcester, Massachusetts||Polar Park||9,508|
|Southeast||Charlotte Knights||1976||Chicago White Sox||1999||Charlotte, North Carolina||Truist Field||10,200|
|Durham Bulls||1980||Tampa Bay Rays||1998||Durham, North Carolina||Durham Bulls Athletic Park||10,000|
|Gwinnett Stripers||2009||Atlanta Braves||1965||Lawrenceville, Georgia||Coolray Field||10,427|
|Jacksonville Jumbo Shrimp||1962||Miami Marlins||2021||Jacksonville, Florida||121 Financial Ballpark||11,000|
|Memphis Redbirds||1998||St. Louis Cardinals||1998||Memphis, Tennessee||AutoZone Park||10,000|
|Nashville Sounds||1978||Milwaukee Brewers||2021||Nashville, Tennessee||First Horizon Park||10,000|
|Norfolk Tides||1961||Baltimore Orioles||2007||Norfolk, Virginia||Harbor Park||11,856|
|Division||Team||Founded||MLB Affiliation||Affiliated Since||City||Stadium||Capacity|
|East||Albuquerque Isotopes||2003||Colorado Rockies||2015||Albuquerque, New Mexico||Rio Grande Credit Union Field at Isotopes Park||13,500|
|El Paso Chihuahuas||2014||San Diego Padres||2014||El Paso, Texas||Southwest University Park||9,500|
|Oklahoma City Dodgers||1962||Los Angeles Dodgers||2015||Oklahoma City, Oklahoma||Chickasaw Bricktown Ballpark||9,000|
|Round Rock Express||2000||Texas Rangers||2021||Round Rock, Texas||Dell Diamond||11,631|
|Sugar Land Skeeters||2012||Houston Astros||2021||Sugar Land, Texas||Constellation Field||7,500|
|West||Las Vegas Aviators||1983||Oakland Athletics||2019||Summerlin, Nevada||Las Vegas Ballpark||10,000|
|Reno Aces||2009||Arizona Diamondbacks||2009||Reno, Nevada||Greater Nevada Field||9,013|
|Sacramento River Cats||2000||San Francisco Giants||2015||West Sacramento, California||Sutter Health Park||14,014|
|Salt Lake Bees||1994||Los Angeles Angels||2001||Salt Lake City, Utah||Smith's Ballpark||14,511|
|Tacoma Rainiers||1960||Seattle Mariners||1995||Tacoma, Washington||Cheney Stadium||6,500|
The Triple-A All-Star Game was a single game held between the two affiliated Triple-A leagues--the International League and the Pacific Coast League. Each league fielded a team composed of the top players in their respective leagues as voted on by fans, the media, and each club's field manager and general manager. The event took place every year since 1988 when the first Triple-A All-Star Game was played in Buffalo, New York. Prior to 1998, a team of American League-affiliated Triple-A All-Stars faced off against a team of National League-affiliated Triple-A All-Stars.
Traditionally, the game was held on the day after the mid-summer Major League Baseball All-Star Game. Such games mark a symbolic halfway-point in the season, despite occurring later than the actual halfway-point of most seasons. Both Triple-A leagues shared a common All-Star break, with no regular-season games scheduled for two days before the All-Star Game itself. Some additional events, such as the All-Star Fan Fest and Triple-A Home Run Derby, were held each year during this break in the regular season.
While the 2021 schedule originally included a three-day All-Star break of July 12-14, this was removed after Opening Day was pushed back one month. Team schedules for the 2021 season were subsequently issued without an All-Star break.
Beginning in 2006, the annual Triple-A National Championship Game was held to serve as a single championship game between the champions of the International League and Pacific Coast League to determine an overall champion of Triple-A baseball. It was originally held annually at Chickasaw Bricktown Ballpark in Oklahoma City, and known as the Bricktown Showdown. Starting in 2011, the game was held in a different Triple-A city each year. Previous postseason interleague championships include the Junior World Series (1932-34, 1936-62, 1970-71, 1973-74), Triple-A World Series (1983, 1998-2000), and Triple-A Classic (1988-91).
For the 2021 season, Minor League Baseball extended the Triple-A regular season to October 3, with league champions determined based on regular-season records through the original end date of the season (September 19 for Triple-A East, and September 21 for Triple-A West). The final 10 games of the season, played after those dates, are deemed the "Final Stretch", with the team posting the best winning percentage during that period winning an as-yet unspecified prize.
As a part of professional baseball's pace of play initiatives implemented in 2015, 20-second pitch clocks entered use at Triple-A stadiums in 2015. In 2018, the time was shortened to 15 seconds when no runners are on base. Other significant changes implemented in 2018 included beginning extra innings with a runner on second base and limiting teams to six mound visits during a nine-inning game. For the 2019 season, the number of mound visits was reduced to five, and pitchers were required to face a minimum of three consecutive batters unless the side is retired or the pitcher becomes injured and is unable to continue playing.