SafekipediaMinor League Baseball
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Minor League Baseball (MiLB) is a group of professional baseball teams that are not part of Major League Baseball (MLB). These teams help young players learn and improve. The first minor league started on September 5, 1901, because some teams could not compete with bigger leagues like the National League and American League.
MiLB teams work with MLB teams. MLB teams send players and staff to MiLB teams. Players can move up to the big leagues when they are ready. There are different levels in MiLB. Players start at the lowest level and move up as they get better. These levels include the Rookie League, Single-A, High-A, AA (Double-A), and AAA (Triple-A).
In 2021, MLB made changes to MiLB, reducing the number of teams to 120. These teams are in different places, including Arizona and Florida for spring training. There are also special leagues in places like the Dominican Republic to help players from there. Some teams not connected to MLB are called Partner Leagues.
History
The first professional baseball league, the National Association of Professional Base Ball Players, started in 1871. It had all professional teams, but it was hard to keep things fair because some teams had more money than others. The National League began in 1876, only letting the strongest teams join.
Minor leagues started as groups of teams that were not strong enough to join the National League. One of the first true minor leagues was the Northwestern League in 1883. It was a permanent organization, unlike earlier groups.
In 1901, leaders of minor leagues met in Chicago and formed the National Association of Professional Baseball Leagues (NAPBL). This group helped minor leagues stay independent.
In 1921, Major League Baseball (MLB) and Minor League Baseball (MiLB) agreed that MLB teams could own minor league teams. This helped MLB develop young players before they joined the big leagues. Over time, minor leagues became very dependent on MLB for money and players.
After World War II, minor leagues were very popular, but television made many fans choose to watch major league games instead. Minor leagues agreed to let MLB show games in their areas in return for money.
In 2021, MLB made big changes to minor leagues, reducing the number of teams and levels.
Classification history
19th century
The first classifications for minor league baseball started around 1890. These levels helped protect player contracts and agreements between teams.
20th century
After the National Association of Professional Baseball Leagues began in 1901, the classifications changed. By 1902, leagues were grouped into different classes like Class A, B, C, and D.
Additional levels were added before World War II, including Class AA in 1912 and Class E in 1937 for new players.
Postwar changes
In 1946, new levels were created. Class AAA, called Triple-A, was introduced, and some leagues were moved to this level. The "Open" classification was added in 1952 for one league, but it returned to Triple-A in 1958.
Reorganization of 1963
A big change happened in 1963 because fewer teams were joining. Some leagues stopped, and others changed levels. Lower levels were dropped because they couldn’t keep going.
Changes between 1963 and 2021
The system stayed mostly the same until 2020. Leagues were grouped into six classes: Triple-A, Double-A, Class A-Advanced, Class A, Class A Short Season, and Rookie. Rookie had further divisions.
Reorganization of 2021
In 2021, Major League Baseball made big changes. Many teams lost their affiliations, and leagues were renamed. The classifications were simplified, and new leagues were created for different levels. The number of teams was reduced, and some leagues were shut down or renamed.
| Class | Aggregate population of cities in the league | Salary cap (per month) team / player | Draft fee† | Protection fee‡ |
|---|---|---|---|---|
| Class A | more than 1 million | $1800 / $175 | n/a | $50 |
| Class B | 400,001 to 1 million | $1000 / $125 | $300 | $30 |
| Class C | 200,001 to 400,000 | $800 / $100 | $200 | $20 |
| Class D | up to 200,000 | $700 / $75 | $100 | $10 |
| Team | Previous league | Previous class | New league | Type |
|---|---|---|---|---|
| Auburn Doubledays | New York–Penn League | A–Short Season | Perfect Game League | Collegiate |
| Batavia Muckdogs | New York–Penn League | A–Short Season | Perfect Game League | Collegiate |
| Billings Mustangs | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Bluefield Blue Jays | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Boise Hawks | Northwest League | A–Short Season | Pioneer League | Independent |
| Bristol Pirates | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Burlington Bees | Midwest League | A | Prospect League | Collegiate |
| Burlington Royals | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Charlotte Stone Crabs | Florida State League | A–Advanced | Folded | |
| Clinton LumberKings | Midwest League | A | Prospect League | Collegiate |
| Danville Braves | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Elizabethton Twins | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Florida Fire Frogs | Florida State League | A–Advanced | Folded | |
| Frederick Keys | Carolina League | A–Advanced | MLB Draft League | Collegiate |
| Grand Junction Rockies | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Great Falls Voyagers | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Greeneville Reds | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Hagerstown Suns | South Atlantic League | A | Folded | |
| Idaho Falls Chukars | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Jackson Generals | Southern League | AA | Folded | |
| Johnson City Cardinals | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Kane County Cougars | Midwest League | A | American Association | Independent |
| Kingsport Mets | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Lancaster JetHawks | California League | A–Advanced | Folded | |
| Lexington Legends | South Atlantic League | A | Atlantic League | Independent |
| Lowell Spinners | New York–Penn League | A–Short Season | Folded | |
| Mahoning Valley Scrappers | New York–Penn League | A–Short Season | MLB Draft League | Collegiate |
| Missoula PaddleHeads | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Northern Colorado Owlz | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Norwich Sea Unicorns | New York–Penn League | A–Short Season | Futures League | Collegiate |
| Ogden Raptors | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Princeton Rays | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Pulaski Yankees | Appalachian League | Rookie Advanced | Appalachian League | Collegiate |
| Rocky Mountain Vibes | Pioneer League | Rookie Advanced | Pioneer League | Independent |
| Salem-Keizer Volcanoes | Northwest League | A–Short Season | Mavericks League | Independent |
| State College Spikes | New York–Penn League | A–Short Season | MLB Draft League | Collegiate |
| Staten Island Yankees | New York–Penn League | A–Short Season | Folded | |
| Trenton Thunder | Eastern League | AA | MLB Draft League | Collegiate |
| Tri-City ValleyCats | New York–Penn League | A–Short Season | Frontier League | Independent |
| Vermont Lake Monsters | New York–Penn League | A–Short Season | Futures League | Collegiate |
| West Virginia Black Bears | New York–Penn League | A–Short Season | MLB Draft League | Collegiate |
| West Virginia Power | South Atlantic League | A | Atlantic League | Independent |
| Williamsport Crosscutters | New York–Penn League | A–Short Season | MLB Draft League | Collegiate |
Organization
Minor League Baseball is a group of professional baseball teams that are not part of Major League Baseball. These teams are connected to MLB teams and help develop players who might one day play in the big leagues.
As of the 2022 season, minor leagues are split into four main levels: Triple-A, Double-A, High-A, and Single-A. MLB teams may also have rookie teams in places like the Arizona Complex League, Florida Complex League, and the Dominican Summer League. While MLB teams play 162 games, minor league seasons are shorter.
Triple-A
Main article: Triple-A (baseball)
Triple-A is the highest level of minor league baseball. It includes two leagues: the International League with 20 teams and the Pacific Coast League with 10 teams. These leagues were called Triple-A East and Triple-A West in 2021. Triple-A has teams along the Atlantic coast, the Midwest, the Pacific coast, and the southwest.
Both young players and more experienced players can be found in Triple-A. Teams often keep players here who are on their 40-man roster but not currently playing in the majors.
Double-A
Main article: Double-A (baseball)
Double-A has three leagues: the Eastern League with 12 teams in the Northeast and Mid-Atlantic, the Southern League with 8 teams in the Deep South, and the Texas League with 10 teams in the Southwest and Great Plains.
Many top young players are in Double-A, getting ready to move to the majors.
High-A
Main article: High-A
High-A is the level below Double-A. It has three leagues: the Midwest League with 12 teams in the Midwest, the Northwest League with 6 teams in the Pacific Northwest, and the South Atlantic League with 12 teams in the eastern states.
Players in High-A are often moving up for the second or third time. Some new players from college may start here.
Single-A
Main article: Single-A
Single-A is the level below High-A. It has three leagues: the California League with 8 teams in California, the Carolina League with 12 teams, and the Florida State League with 10 teams. Most teams in the Florida State League are owned by MLB teams and use their spring training facilities.
Players in Single-A are usually moving up from rookie leagues or are new players joining professional baseball.
Rookie
Minor league rookie teams play shorter seasons, usually starting in mid-June and ending in late August. These teams are in the Arizona Complex League, Florida Complex League, and the Dominican Summer League.
Rookie leagues have about 60 games and are where new players practice their skills.
| Level | Active roster size: 10–11 | Player restrictions: 100 |
|---|---|---|
| Triple-A | 28 players | No restrictions |
| Double-A | 28 players | No restrictions |
| High-A | 30 players | No more than 2 players and 1 player-coach with 6 or more years of minor-league experience |
| Single-A | 30 players | No more than 2 players with 5 or more years of minor-league experience |
| U.S.-based Rookie | No limit | No more than 3 players with 4 or more years of minor-league experience |
| International Rookie | 35 players | No players with 4 or more years of minor-league experience |
Leagues and affiliations
Main article: List of Minor League Baseball leagues and teams
Minor leagues
Minor League Baseball is made up of several leagues that are affiliated with Major League Baseball teams. These leagues are organized into different levels, from the highest (Triple-A) to the lowest (Rookie).
Triple-A
Double-A
High-A
Single-A
Rookie
Off-season leagues
Showcase league
Partner leagues
- American Association
- Atlantic League
- Frontier League
- Pioneer League
Major League affiliations
Map
!Bisons
!Knights
!Clippers
!Bulls
!Stripers
!Indians
!Cubs
!Jumbo Shrimp
!IronPigs
!Bats
!Redbirds
!Sounds
!Tides
!Storm Chasers
!Red Wings
!RailRiders
!Saints
!Mets
!Mud Hens
!Red Sox
!Isotopes
!Chihuahuas
!Aviators
!Comets
!Aces
!Express
!River Cats
!Bees
!Space Cowboys
!Rainiers
!Sod Poodles
!Travelers
!Hooks
!RoughRiders
!RockHounds
!Naturals
!Missions
!Cardinals
!Drillers
!Wind Surge
!RubberDucks
!Curve
!Rumble Ponies
!Baysox
!SeaWolves
!Senators
!Yard Goats
!Fisher Cats
!Sea Dogs
!Fightin Phils
!Flying Squirrels
!Patriots
!Shuckers
!Barons
!Lookouts
!Clingstones
!Biscuits
!Blue Wahoos
!Trash Pandas
!Smokies
!Sky Carp
!Kernels
!Dragons
!TinCaps
!Loons
!Captains
!Lugnuts
!Chiefs
!River Bandits
!Cubs
Cubs
!Whitecaps
!Timber Rattlers
!Tourists
!Hot Rods
!Cyclones
!Keys
!Grass-hoppers
!Drive
!Spartanburgers
!Renegades
!BlueClaws
!Emperors
!Blue Rocks
!Dash
!Emeralds
!AquaSox
!Hops
!Indians
Indians
!Dust Devils
!Canadians
!GreenJackets
!RiverDogs
!Fireflies
!Shorebirds
!Woodpeckers
!Nationals
!Crawdads
!Cannon Ballers
!Howlers
!Pelicans
!RidgeYaks
!Warbirds
!Marauders
!Threshers
!Tortugas
!Blue Jays
!Mighty Mussels
!Hammerheads
!Flying Tigers
!Cardinals
Cardinals
!Mets
Mets
!Tarpons
!Grizzlies
!66ers
!Storm
Storm
!Tower Buzzers
!Quakes
!Giants
!Ports
!Rawhide
Current team locations:
- International League
- Pacific Coast League
- Eastern League
- Southern League
- Texas League
- Midwest League
- Northwest League
- South Atlantic League
- California League
- Carolina League
- Florida State League
Team rosters
Classification hierarchy
The following classifications, listed from highest to lowest, have existed since the National Association of Professional Baseball Leagues (the formal name of Minor League Baseball) was established prior to the 1902 season. Only seasons where a change was made to the hierarchy are listed; class introductions after 1902 appear in bold font, while class eliminations appear in italics. Not all defined classifications were used each season.
Notes:
- High-A was formerly Class A-Advanced (A-Adv) before 2021
- Class A was officially known as Low-A during the 2021 season
- A (Short) denotes Class A Short Season
- Rk-Adv denotes Rookie Advanced
- Rk denotes Rookie
| Triple-A | Double-A | High-A | Single-A | ||||
|---|---|---|---|---|---|---|---|
| IL | International League | EL | Eastern League | MWL | Midwest League | CAL | California League |
| PCL | Pacific Coast League | SL | Southern League | NWL | Northwest League | CAR | Carolina League |
— | TL | Texas League | SAL | South Atlantic League | FSL | Florida State League | |
| 1902 | 1912 | 1936 | 1937 | 1946 | 1952 | 1958 | 1963 | 1965 | 1990 | 1991 | 2021 |
|---|---|---|---|---|---|---|---|---|---|---|---|
A B C D | AA A B C D | AA A1 A B C D | AA A1 A B C D E | AAA AA A B C D | Open AAA AA A B C D | AAA AA A B C D | AAA AA A Rk | AAA AA A A (Short) Rk | AAA AA A-Adv A A (Short) Rk | AAA AA A-Adv A A (Short) Rk-Adv Rk | AAA AA High-A A Rk |
A1 E | Open | B C D | A (Short) Rk-Adv |
Players
Major league teams can only use players who are on their main team roster for games. These players are chosen from a list of 40 players, called the 40-man roster. Since the 2020 season, each team has 26 players on their active roster for regular games, and 27 for doubleheaders. From September 1 to the end of the season, teams can have up to 28 players on their roster.
Players not on the active roster are either hurt or playing in the minor leagues, usually at the Triple-A or Double-A level. A team's director of player development decides where each player will play, working with coaches and managers. After spring training, players are assigned to minor league teams. New players usually start playing in June after signing contracts. Players can move up or down between teams during the season based on how they are doing, or they might be released. Some released players join independent baseball teams.
Salaries and compensation
Minor league players are professional athletes, but they earn less than major league players. The main team pays for players' salaries and benefits, while the minor league team pays for travel and other costs. Players with major league experience or on the 40-man roster earn more, while others earn less as they develop their skills. Many players get signing bonuses, especially early-round draft picks.
Rehabilitation assignments
Injured major league players often go to minor league teams to practice and get back in shape. They usually stay for one or two weeks, depending on their injury. These players still get their major league pay and better facilities than minor league players. For example, Joe Mauer of the Minnesota Twins played for a minor league team in 2011 while recovering from knee surgery, and Mike Trout of the Los Angeles Angels did the same in 2017.
| Level | Minimum annual salary | Minimum annual salary if on 40-man roster | Minimum annual salary with MLB experience |
|---|---|---|---|
| Triple-A | $35,800 | $60,300 | $120,600 |
| Double-A | $30,250 | ||
| High-A | $27,300 | ||
| Single-A | $26,200 | ||
| US-based Rookie | $19,800 | ||
| Arizona Fall League | $6,000 | ||
| Foreign-based Rookie | $3,000 |
Umpires
Umpires in minor league baseball are trained and checked by Minor League Baseball Umpire Development (MiLBUD). They are checked eight times each season and can move up in rank based on how well they do. Every year in March, MiLBUD holds a course for new umpires, usually taking the best students from special training schools.
To become an umpire, you must go to one of two training schools in Florida: the Harry Wendelstedt Umpire School or the Minor League Baseball Umpire Training Academy. These schools teach students for five weeks, and only a few move on to further training. The umpire development program began in 1964 to find better-trained umpires.
Umpires must have a high school diploma or a G.E.D., be athletic, have good vision, and strong communication skills. They also need to have trained at one of the two professional schools.
Main article: 2006 Minor League Baseball umpire strike
Ownership
Minor League Baseball teams are usually owned by different people or groups. They work closely with one Major League Baseball team. These teams have special agreements about how they will work together. Some Minor League teams are even owned by the same company that owns their Major League team.
As of December 2025, a company called Diamond Baseball Holdings owns 48 of the 120 Minor League teams. Major League Baseball has rules to make sure no one company can own too many teams. The agreements between Major and Minor League teams used to last only two or four years, but now they last for ten years. Some teams have worked together for a very long time. For example, the Omaha Storm Chasers have been connected to the Kansas City Royals since 1969.
Presidents
MiLB was run by a central office until 2021, when MLB took over all important decisions. The minor league office was in St. Petersburg, Florida starting in 1973. Before MLB took control, 11 people were president of MiLB.
Independent baseball
Main article: Independent baseball league
Independent baseball leagues are professional teams in the United States and Canada that are not part of Minor League Baseball or managed by the Commissioner of Baseball. These leagues started in the early 1900s and became more common again after 1993.
Before 1902, these leagues worked mostly on their own. After that, many joined a larger group, but a few stayed independent. Some stayed independent only for a short time, like the California League and the United States Baseball League. Others, like the Federal League, played at a level close to the top major leagues for a couple of years.
Between 1915 and 1993, there were only a few independent leagues. Examples include the Carolina League and the Provincial League in Quebec. After 1992, many new independent leagues started because of new rules in organized baseball. Today, there are seven active independent leagues, and four of them work with Major League Baseball teams.
Awards
For additional awards, see Baseball awards § U.S. minor leagues.
MiLBY Awards
The MiLBY Awards are given in nine categories. In five categories, winners are chosen at each level of Minor League Baseball. In three categories, one overall winner is picked. There is also a Promo of the Year category with several subcategories.
Other player awards
- MiLB Topps Minor League Player of the Year Award
- MiLB George M. Trautman Awards
- MiLB Joe Bauman Home Run Award
- Baseball America Minor League Player of the Year Award
- The Sporting News Minor League Player of the Year Award
- USA Today Minor League Player of the Year Award
Major awards
- Organization of the Year Award
- Rawlings Woman Executive of the Year
- Warren Giles Award
- King of Baseball
- Larry MacPhail Award
- Sheldon "Chief" Bender Award
- Mike Coolbaugh Award
- John H. Moss Community Service Award
- Charles K. Murphy Patriot Award
Top 100 teams
In 2001, MiLB made a list of the 100 best minor-league baseball teams.
Broadcasting
Radio
Most minor-league baseball teams have local radio stations that broadcast their games. These stations are usually only one or two per team.
Television
You can watch minor-league games on Stadium and the MLB Network. Many teams also have deals with local TV channels. For example, the Triple-A Indianapolis Indians showed 35 home games on WISH-TV in 2021.
Streaming media
MiLB.TV is the online service for watching minor-league games, similar to MLB.tv. Starting in 2021, it offered games from all Triple-A and Double-A teams, plus some games from other levels. All games are also free on the Bally Live App.
TuneIn offers free audio streams of minor-league games through the MiLB.TV website.
Attendances
Here are the top 50 Minor League Baseball teams by average home attendance in 2025:
Source:
Images
Related articles
This article is a child-friendly adaptation of the Wikipedia article on Minor League Baseball, available under CC BY-SA 4.0.
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