Minor League Baseball (MiLB) is a hierarchy of professional baseball minor leagues in the Americas that compete at levels below Major League Baseball (MLB) and help prepare players to join major league teams. Those teams which are affiliated with MLB teams operate under the Commissioner of Baseball within the scope of organized baseball. Several leagues, known as independent baseball leagues, consist of teams with no affiliation to MLB teams. Starting with the 2021 season, the number of MLB-affiliated minor leagues with teams in the United States and Canada has been reduced to 11, with a total of 120 teams (four per each of the 30 MLB franchises, excluding rookie league teams). There is also an MLB-affiliated rookie league in the Dominican Republic.

Early history

The earliest professional baseball league, the National Association of Professional Base Ball Players of 1871 to 1875, comprised all fully professional teams. This system proved unworkable, however, as there was no way to ensure competitive balance, and financially unsound clubs often failed in midseason. This problem was solved in 1876 with the formation of the National League (NL), with a limited membership which excluded less competitive and financially weaker teams. Professional clubs outside the NL responded by forming regional associations of their own. There was a series of ''ad hoc'' groupings, such as the New England Association of 1877 and the Eastern Championship Association of 1881. These were loose groups of independent clubs which agreed to play a series of games over the course of one season for a championship pennant. The first true minor league is traditionally considered to be the Northwestern League of 1883 to 1884. Unlike the earlier minor associations, it was conceived as a permanent organization. It also, along with the NL and the American Association (AA), was a party to the National Agreement of 1883. Included in this was the agreement to respect the reserve lists of clubs in each league. Teams in the NL and the AA could only reserve players who had been paid at least $1,000. Northwest League teams could reserve players paid $750, implicitly establishing the division into major and minor leagues. Over the next two decades, more minor leagues signed various versions of the National Agreement. Eventually, the minor leagues joined together to negotiate jointly. In the late 1890s, the Western League run by Ban Johnson decided to challenge the NL's position. In 1900, he changed the name of the league to the American League (AL) and vowed to make deals to sign contracts with players who were dissatisfied with the pay and terms of their deals with the NL. This led to a turf war that heated up in 1901 enough to concern Patrick T. Powers, president of the Eastern League, and many other minor league owners about the conflict potentially affecting their organizations. Representatives of the different minor leagues met at the Leland Hotel in Chicago on September 5, 1901. In response to the NL–AL battle, they agreed to form the ''National Association of Professional Baseball Leagues'', called the NAPBL, or NA. (The NA uses the trade name Minor League Baseball today.) The purpose of the NAPBL at the time was to maintain the independence of the leagues involved. Several did not sign the agreement and continued to work independently. Powers was made the first president of the NAPBL, whose offices were established in Auburn, New York. In 1903, the conflict between the AL and NL ended in the National Agreement of 1903. The NAPBL became involved in the later stages of the negotiations to develop rules for the acquisition of players from their leagues by the NL and the AL. The 1903 agreement ensured that teams would be compensated for the players that they had taken the time and effort to scout and develop, and no NA team was required to sell their players, although most did because the cash was an important source of revenue for most teams. The NA leagues were still fiercely independent, and the term ''minor'' was seldom used in reference to them, save by the major-market sportswriters. Sports news, like most news generally, often did not travel far in the days before radio and television, so, while the leagues often bristled at the major market writers' descriptions, they viewed themselves as independent sports businesses. Many baseball writers of that time regarded the greatest players of the minor leagues, such as Buzz Arlett, Jigger Statz, Ike Boone, Buddy Ryan, Earl Rapp and Frank Shellenback, as comparable to major league players. Leagues in the NA would not be truly called minor until Branch Rickey developed the first modern farm system in the 1930s. The Commissioner of Baseball, Kenesaw Mountain Landis fought Rickey's scheme, but, ultimately, the Great Depression drove teams to establish systems like Rickey's to ensure a steady supply of players, as many NA and independent teams could not afford to keep their doors open without the patronage of Major League Baseball. The leagues of the NA became subordinate to the major leagues, creating the first minor leagues in the current sense of the term. Other than the Pacific Coast League (PCL), which under its president Pants Rowland tried to become a third major league in the Western states, the other leagues maintained autonomy in name only, being totally economically dependent upon the AL and NL. In 1922, the United States Supreme Court decision ''Federal Baseball Club v. National League'' (259 U.S. 200), which grants baseball a special immunity from antitrust laws, had a major effect on the minor leagues. The special immunity meant that the AL and NL could dictate terms under which every independent league did business. By 1925, major league baseball established a flat-fee purchase amount of $5,000 for the contract of any player from an NA member league team. This power was leveled primarily at the Baltimore Orioles, then a Triple-A team that had dominated the minors with stars.


With some exceptions, teams in the affiliated minor leagues are generally independently owned and operated but are directly affiliated with one major league team through a standardized player development license (PDL). Some minor league teams are directly owned by their major league parent club, such as the Springfield Cardinals, owned by the St. Louis Cardinals, and all of the New York Mets' affiliates except the Binghamton Rumble Ponies. With the reorganization of 2021, the standard length for a PDL is ten years. Previously, affiliations were for only two or four years, with affiliation changes being fairly frequent, though many relationships have been renewed and endure for extended time periods. For example, the Omaha Storm Chasers (formerly the Omaha Royals and Omaha Golden Spikes) have been the Triple-A affiliate of the Kansas City Royals since the Royals joined the American League in 1969, but the Columbus Clippers, having being affiliated with the New York Yankees since 1979, changed affiliations to the Washington Nationals in 2007, and again changed to the Cleveland Indians two years later in 2009. Generally, the parent major league club pays the salaries and benefits of uniformed personnel (players and coaches) and provides bats and balls, while the minor league club pays for in-season travel and other operational expenses. The longest continuous affiliations are between the Philadelphia Phillies and their Double-A affiliate, the Reading Fightin Phils and between the Detroit Tigers and their Low-A affiliate, the Lakeland Flying Tigers, both of which date to 1965. Both Reading and Lakeland are now owned outright by their parent major league clubs.

Current system

Entering the 2021 season, the minor league classification system divides leagues into one of four classes: Triple-A (AAA), Double-A (AA), High-A (A+), and Low-A (A). MLB franchises may also maintain a complex-based rookie team in the Arizona League or Gulf Coast League, and international summer baseball teams in the Dominican Summer League. A 2011 Double-A game between the Carolina_Mudcats_.html" style="text-decoration: none;"class="mw-redirect" title="Carolina Mudcats (1991–2011)">Carolina Mudcats ">Carolina Mudcats (1991–2011)">Carolina Mudcats


This classification currently includes two affiliated leagues: Triple-A East and Triple-A West, which replaced the International League and the Pacific Coast League, respectively. For most of the 20th century, Triple-A also included the American Association, based in the Midwest, but that league disbanded with its clubs absorbed by the other two leagues, as part of a reorganization of the Triple-A level in 1997. Both young players and veterans play for Triple-A teams. Parent clubs often hold players who are on the 40-man roster, but not on the active MLB roster, at the Triple-A level. Such players are eligible to be added to a team's active major league roster. For teams in contention for a pennant late in a season, it gives them fresh players, while for teams not in contention, it gives them an opportunity to evaluate their second-tier players against major league competition. Some Triple-A players are "career minor leaguers", former prospects whose skill growth has halted and who are not likely to advance to MLB, unless as a temporary replacement.


There are currently three leagues in this classification: Double-A Northeast, Double-A South and Double-A Central, which replaced the Eastern League, Southern League, and the Texas League, respectively. Some players jump to the majors from this level, as many of the top prospects are put here to play against each other rather than against minor and major league veterans in Triple-A. A small handful of players might be placed here to start, usually veterans from foreign leagues with more experience in professional baseball. The expectation is usually that these veteran players will be in the majors by the end of the season, as their salaries tend to be higher than those of most prospects.


One level below Double-A is the High-A level, also known as "Class A-Advanced" and sometimes abbreviated "Class A+". Beginning in 2021, this classification has three leagues: High-A East, High-A Central, and High-A West, which succeed the Carolina League, Midwest League, and Northwest League, respectively, with the Midwest League having previously been a Low-A League and the Northwest League having previously been a short-season league. This level of play is often a second or third promotion for a minor league player, although a few high first-round draftees, particularly those with college experience, begin at this level.


Below the High-A level is Low A, also known as "Single-A" or "Class A". Beginning in 2021, this classification has three leagues: Low-A East, Low-A Southeast, and Low-A West, which succeed the South Atlantic League, Florida State League, and California League, respectively, the latter two having been High-A leagues. These leagues are a mix of players moving up from Rookie leagues, as well as the occasional experienced first-year player. Most of the teams in Low-A Southeast are owned by major league parent clubs and use their spring training complexes.


MiLB leagues with the Rookie classification play a shortened season, starting in mid-June and ending in late August or early September. This lowest level of minor league baseball consists of two US-based leagues, the Arizona League and Gulf Coast League, and one Caribbean-based league, the Dominican Summer League. The US-based Rookie leagues play a 60-game schedule and are usually called "complex leagues" because games are played at their parent clubs' spring training complexes. Rosters comprise newly drafted players who are not yet ready for a higher level of play. These leagues are intended almost exclusively to allow players to hone their skills; no admission is charged and no concessions are sold.

Classification history

19th century

The earliest classifications used in the minor leagues began circa 1890, for teams that were party to the National Agreement of 1883. The different levels represented different levels of protection for player contracts and reserve clauses: * Class A: contracts and reserve lists protected * Class B: contracts and reserve lists protected, but a major league team can draft a player for a set price * Class C: contracts protected * Class D: contracts protected, but any high class can draft a player for a set price * Class E/F: no protection

20th century

After the National Association of Professional Baseball Leagues was founded in 1901, classifications were redefined: Draft fee set an amount for a team in a higher class to select a player; n/a for Class A as it would be up to each team to negotiate with an interested major league club.
Protection fee reserved a player to a team, even after a contract expired, preventing the player for seeking employment with any other team. All minor leagues were classified, and had the following assignments entering the 1902 season: * Class A: Eastern League, Western League * Class B: Connecticut State League, New England League, New York State League, Pacific Northwest League, Southern League, Three-I League * Class C: ''no league until 1903'' * Class D: Cotton States League, Iowa–South Dakota League, Missouri Valley League, North Carolina League, Pennsylvania State League, Texas League Additional classifications added prior to World War II were: * Class AA ("Double-A"): added in 1912 as the new highest level * Class A1: added in 1936, between Class A and Class AA * Class E: added in 1937, as the new lowest level (only used by one league, for part of the 1943 season) Through 1945, the highest level was Double-A. In 1946, with the minor leagues poised for unprecedented growth, the higher-level classifications were changed. Class AAA ("Triple-A") was created and the three Double-A circuits (the Pacific Coast League, International League, and the American Association) were reclassified into Triple-A. Class A1 (comprising the Texas League, which had last operated in 1942, and the Southern Association) became Class AA. Prior to 1963, Class A was a higher classification than it is today. In 1946, Class A consisted of the Eastern League and the original South Atlantic League (or "Sally League"), and it would soon include the Western League (1947–1958), Central League (1948–1951) and Western International League (1952–1954). The Western International League became the Class B Northwest League in 1955, and the Western and Central loops folded. The remaining Class A leagues ascended to Double-A in the 1963 reorganization. Postwar Class A cities included communities such as Vancouver, Omaha, Colorado Springs, Charlotte, Scranton and Allentown, which would establish themselves as Triple-A venues, and Denver, which would get its own major league team, the Colorado Rockies, in 1993. The lower levels of the minors were ranked Classes B through D in descending order, with Class D being the equivalent of today's Rookie leagues. With the exception of the 1952–1957 Open classification experiment for the Pacific Coast League, this structure would remain intact through 1962. Major reorganizations took place in 1963 and 2021.

Defunct classifications

The following classifications were only used prior to 1963:


The Pacific Coast League (PCL), which had been rated Triple-A since 1946, was the only minor league to obtain Open classification, which existed from 1952 to 1957. At this time, the major leagues only extended as far west as Missouri and as far south as Washington, D.C. This classification severely restricted the rights of the major leagues to draft players out of the PCL, and at the time it seemed like the PCL would eventually become a third major league. The PCL would revert to Triple-A in 1958 due to increasing television coverage of major league games and in light of the Dodgers and Giants moving to Los Angeles and San Francisco, respectively.

Class A1

The forerunner to the modern Double-A classification, the A1 level existed from 1936 through 1945. In 1936, two Class A circuits, the Texas League and the Southern Association, were upgraded to "Class A1" to signify their continued status as one step below the highest classification, then Double-A, yet a notch above their former Class A peers, the New York–Pennsylvania League and Western League.

Class B, C and D

From 1902 through 1962, there were Class B, C, and D leagues. The Class D of that period would be equivalent to the Rookie level today. The other class designations disappeared because leagues of that level could not sustain operation during a large downturn in the financial fortunes of minor league baseball in the 1950s and 1960s caused by the rise of television broadcasts of major league sports across broad regions of the country. The impact of the Korean War in 1950 caused a player shortage in most cities in Class D and Class C.

Class E

Class E was established in 1937, for players with no professional experience in Class D or higher. The only Class E league that existed was the four-team Twin Ports League, which operated for less than a full season in 1943.

Reorganization of 1963

The 1963 reorganization was caused by the club and league contraction of the 1950s and early 1960s. In 1949, the peak of the post-World War II minor league baseball boom, 438 teams in 59 leagues were members of the National Association of Professional Baseball Leagues. By the end of 1963, only 15 leagues above Rookie-level survived in the United States and Canada. After the 1962 season, the Triple-A American Association—which had lost key markets such as Milwaukee, Kansas City, Minneapolis, St. Paul and Houston to the Major Leagues since 1953—disbanded. The surviving International and Pacific Coast leagues absorbed the four remaining American Association franchises. Meanwhile, at the Double-A level and below there were even more significant changes: * The two existing Class A leagues—the Eastern and South Atlantic—were upgraded to Double-A, joining the Texas League and the unaffiliated Mexican League, then Double-A, as members of this classification. This move was caused by the disbanding of the Southern Association after 1961, leaving the six-team Texas League as the only U.S.-based Double-A circuit in 1962. In addition, many Major League parent teams had frequently treated the pre-1963 Eastern and South Atlantic leagues as ''de facto'' Double-A circuits, one step (rather than two) below Triple-A. * The Class B Carolina League and Northwest League, the Class C California League, Pioneer League and Northern League, and the Class D Florida State League, Georgia–Florida League, Midwest League, New York–Penn League, and Western Carolinas League were all designated Class A leagues. The unaffiliated Class C Mexican Central League was also designated as Class A. * The Class D Appalachian League, then the only "short-season" circuit, was given a new designation as a "Rookie" league. As part of the 1963 reorganization, Major League clubs increased their commitments to affiliate with minor league teams through Player Development Contracts, outright ownerships, or shared affiliations and co-op arrangements.

Further changes after 1963

The minor league system that evolved following the 1963 reorganization remained in place through 2020, categorizing leagues into one of six classes: Triple-A (AAA), Double-A (AA), Class A-Advanced (High A or A+), Class A (Low A), Class A Short Season, and Rookie. Furthermore, Rookie was further informally subdivided into Rookie Advanced, complex-based Rookie, and international summer baseball. *Triple-A: The American Association was revived as a Triple-A league in 1969 and flourished with the minor league baseball boom of the 1980s and 1990s. However, all of its teams were again absorbed into the International and Pacific Coast leagues in 1998 as part of a sweeping reorganization of the minors' top classification. The American Association and the International League also played an interlocking schedule during the late 1980s as part of the Triple-A Alliance. The Mexican League was upgraded from Double-A to Triple-A in 1967. *Double-A: In 1964, the South Atlantic League changed its name to its current identity, the Southern League. Because of continued contraction (and Major League expansion) that left each circuit with only seven teams, the Texas and Southern leagues merged into the 14-team Dixie Association in 1971. The arrangement lasted only for that season and the records and history of the Texas and Southern loops were kept distinct. In 1972, each league added an eighth team, rebalancing their schedules. They resumed their former, separate identities, and returned to prosperity with the revival of minor league baseball that began in the 1980s. *Class A: two additional classifications evolved from Class A. Under the rules governing the affiliated minor leagues (specifically, Rule 51 in ''The Official Professional Baseball Rules Book''), these became separate classifications, despite the similarity in name: ** The Class A Short Season designation was created in 1965, and the Northern League and Northwest League moved from "full season" Class A into the new classification, with the New York–Penn League joining them in 1967. Prior to the classification being eliminated before the 2021 season, the New York–Penn League and Northwest League were the only active leagues at this level. These leagues played a 76-game season, starting in mid-June and ending in early September, with only a few off-days during the season. The late start of the season was designed to allow college players to complete their college seasons in the spring, be selected in the MLB draft in June, signed, and then immediately placed in a competitive league. Players in short-season leagues were a mixture of newly signed draftees who were considered more advanced than other draftees, and second-year pros who were not ready, or for whom there was not space at a higher level to move up. Second-year pros were often assigned to "extended spring training" in Florida or Arizona during April and May before reporting to their short-season leagues. ** The Class A-Advanced classification, one rung below Double-A, came to be used with the California, Carolina and Florida State leagues, splitting the Class A level even further. The Georgia–Florida League disbanded after the 1963 season, while the Northern League played its last year in official minor league baseball in 1971. In 1980, the Western Carolinas League changed its identity to become the modern incarnation of the South Atlantic League. Entering the 2021 season, three new "High-A" leagues were introduced in replacement of prior leagues at this level. *Rookie Advanced: The Appalachian League and Pioneer League became known as "Rookie Advanced" leagues, before the classification was eliminated prior to the 2021 season. The players in these leagues were thought to be further along in their development than players in the pure Rookie leagues, and hence games were more competitive. Teams in these leagues were allowed to sell concessions and charge admission. *Rookie: In 1964, the Pioneer League stepped down from Class A to Rookie league status, and the first "complex-based" leagues, the Sarasota Rookie League and the Cocoa Rookie League, made their debuts. The Sarasota Rookie League underwent a name change to the Florida Rookie League in 1965 before becoming the modern Gulf Coast League the next season. The Cocoa Rookie League lasted only one season, and the Florida East Coast League of 1972, based in the same region of the state, also existed for only one year. In 1989, a counterpart to the Gulf Coast League, the Arizona League, made its debut and it continues to operate as a Rookie-level league for MLB teams with spring training facilities based in Arizona. There have also been some failed start-up leagues. During the 1970s, three official minor leagues (members of NAPBL) attempted unsuccessfully to revive unaffiliated baseball (teams not associated with specific MLB franchises) within the organized baseball structure. These were the Class A Gulf States League (1976) and Lone Star League (1977), and the Triple-A Inter–American League (1979). None lasted more than a full season.

Reorganization of 2021

In October 2019, ''Baseball America'' reported that Major League Baseball had proposed dramatic changes to MiLB that would take effect after expiration of the Professional Baseball Agreement, which governs the MLB–MiLB relationship, at the end of the 2020 season. (soft paywall) In mid-November 2019, more than 100 members of the United States Congress signed a letter sent to Commissioner of Baseball Rob Manfred opposing the proposal, noting that it "is not in the best interest of the overall game of baseball" and that it would "devastate our communities, their bond purchasers and other stakeholders affected by the potential loss of these clubs." A response from MLB highlighted that the proposal aims to improve player travel and working conditions. On November 21, 2019, Minor League Baseball released a statement, asserting that it is "unnecessary and unacceptable to wipe out one-quarter of minor league teams" and characterized the proposal as a way "to improve the profitability of MLB". Manfred rebuked Minor League Baseball for releasing the negotiations to the public and threatened to cut ties with MiLB altogether. The following changes, which represent the first significant overhaul of minor league classifications since 1963, have since been implemented: * The Major League Baseball draft will be moved to July as part of the MLB All-Star Game activities, and reduced from 40 rounds to 20. * The Rookie-level Appalachian League was converted to a collegiate summer baseball league designed for rising freshmen and sophomores. * The independent American Association, Atlantic League, and Frontier League and formerly Rookie-level Pioneer League will become MLB Partner Leagues, with the ability for MLB clubs to acquire players from the Partner Leagues to affiliated clubs. *The formation of the MLB Draft League, a "showcase league" for players expected to be taken in the annual MLB Draft, that will play a 68-game summer season. Four teams from the New York-Penn League (Mahoning Valley Scrappers, State College Spikes, West Virginia Black Bears, and Williamsport Crosscutters), one from the Eastern League (Trenton Thunder), and one from the Carolina League (Frederick Keys) will make up the initial league when it debuts in May 2021. * Three independent league teams, the St. Paul Saints, the Sugar Land Skeeters, and the Somerset Patriots, will be brought into MiLB. The Skeeters have been announced as the new Triple-A affiliate of the Houston Astros, the Saints have been announced as the new Triple-A affiliate of the Minnesota Twins, and the Patriots have been announced as the Double-A affiliate of the New York Yankees. * The number of MiLB teams, not counting teams in the complex-based Arizona and Gulf Coast Leagues, both of which are directly owned by MLB, would be reduced from 160 to 120. This would also result in the elimination of the Short-Season A and Rookie classifications from the system, apart from the complex-based leagues. * The New York–Penn League was shut down, leaving seven of its teams without an invitation to join another league.

Affiliate invites for 2021

When MLB teams announced their affiliates for the 2021 season on December 9, 2020, each of the 30 MLB teams had one affiliate at four levels—Triple-A, Double-A, High-A, and Low-A—for a total of 120 affiliated teams. Eliminated were "short-season and rookie leagues in the Northeast, the Rockies and the Appalachians, with a majority of those franchises absorbed into collegiate and draft-showcase leagues as previously announced." Approximately 40 teams lost their MLB affiliations, the Fresno Grizzlies moved from Triple A to Low-A, and the majority of surviving clubs at High-A and Low-A swapped levels, with the Florida State League and California League swept down nearly as intact units, the Northwest League and Midwest League promoted with 75% of their teams, the majority of the Carolina League shifting to the South Atlantic League, and the old SAL being parceled out among three leagues.

League realignment

On February 12, 2021, Major League Baseball announced new league alignments for all 120 affiliated Minor League Baseball clubs effective as of the 2021 season. Contrary to previously published reports indicating that realignment would retain the names of the existing minor leagues, Major League Baseball elected to, for the time being, abandon the names of existing minor leagues in favor of a new, class- and region-based naming system. Under this system, the Triple-A class will be divided into two leagues: Triple-A East, consisting of 20 teams aligned into three divisions (Midwest, Northeast, and Southeast); and Triple-A West, consisting of 10 teams aligned into two divisions (East and West). The Double-A class will be divided into three leagues: Double-A Central, consisting of 10 teams aligned into two divisions (North and South); Double-A Northeast, consisting of 12 teams aligned into two divisions (Northeast and Southeast); and Double-A South, consisting of eight teams aligned into two divisions (North and South). Class A-Advanced will be divided into three leagues: High-A Central, consisting of 12 teams aligned into two divisions (East and West); High-A East, consisting of 12 teams aligned into two divisions (North and South); and High-A West, consisting of six teams without divisional alignment. Class A will be divided into three leagues: Low-A East, consisting of 12 teams aligned into three divisions (Central, North, and South); Low-A Southeast, consisting of 10 teams aligned into two divisions (East and West); and Low-A West, consisting of eight teams aligned into two divisions (North and South)


Major league clubs may only use players who are on the team's major league active roster in games; players on the active roster are selected from a 40-man major league reserve list (often called the 40-man roster). Effective with the 2020 Major League Baseball season, the active roster size for each team is 26 players for regular games and 27 players for scheduled doubleheaders, with the roster size expanding to 28 players from September 1 through the end of the regular season. Prior to the 2020 season, the active roster size from the start of the regular season until September 1 was 25 players, with a 26th player allowed for a scheduled doubleheader. From September 1 to the end of the regular season, teams were allowed to expand their active rosters up to 40 players, the size of the major league reserve list. Players on the 40-man reserve list who are not on the team's active roster are generally either on the injured list or playing at some level of the minor leagues (usually at the Triple-A or Double-A level). Players on the 40-man reserve list are eligible for membership in the Major League Baseball Players Association. These minor league players work at the lower end of major league pay scales and are covered by all rules and player agreements of the players association. Minor league players not on the 40-man reserve list are under contract to their respective parent Major League Baseball clubs but have no union. They generally work for far less pay as they develop their skills and work their way up the ladder toward the major leagues. Many players have signing bonuses and other additional compensation that can run into the millions of dollars, although that is generally reserved for early-round draft picks. A major league team's director of player development determines where a given player will be placed in the farm system, in coordination with the coaches and managers who evaluate their talent. At the end of spring training, players both from the spring major camp and minor league winter camp are placed by the major league club on the roster of a minor league team. The director of player development and the general manager usually determine the initial assignments for new draftees, who typically begin playing professionally in June after they have been signed to contracts. The farm system is ever-changing, and the evaluation of players is a constantly ongoing process. The director of player development and his managers meet or teleconference regularly to discuss how players are performing at each level. Personal development, injuries, and high levels of achievement by players in the classes below all steer a player's movement up and down in the class system. Players will play for the team to which they are assigned for the duration of that season unless they are "called up" (promoted to a higher level), "sent down" (demoted to a lower-class team in the major league club's farm system), or released from the farm system entirely. A release from minor-league level used to spell the end of a minor league player's career. In more modern times, released players often sign with independent baseball clubs, which are scouted heavily by major league organizations. Many players get a second or third look from the major league scouts if they improve in the independent leagues. Minor league salaries vary based on class level and length of season; however, the majority of players make less than $10,000 per season. Although not playing at the major league level, minor league players are professional athletes. Minor league players often colloquially refer to the major leagues as "The Show".

Rehabilitation assignments

Players on the injured list (IL) can be sent to the minor leagues to aid in rehabilitation following an injury, typically for one or two weeks. Players are often sent to minor league clubs based on geography and facilities, not necessarily by class for these reassignments. Curt Schilling's recovery from an ankle injury in 2005 included a rehabilitation stint in Pawtucket, Rhode Island, at the Triple-A Pawtucket Red Sox, very close to the home club in Boston. The Cincinnati Reds often send players to their Class A affiliate, the Dayton Dragons, for rehab assignments. Despite Dayton's status as Class A, Dayton is a short drive from the Reds' Great American Ball Park. Former Minnesota Twins star Joe Mauer, who missed most of the first two months of the 2011 season due to a difficult recovery from arthroscopic knee surgery after the 2010 season, reported to Minnesota's Class A-Advanced Florida State League team, the Fort Myers Miracle, which is based in their spring training facility in Fort Myers. In addition, the Miracle manager at the time was Mauer's older brother Jake. The Twins later sent Joe Mauer and pitcher Ricky Nolasco to rehab with the club's Low-A affiliate located across the Minnesota-Iowa border in Cedar Rapids. Mike Trout's first rehab assignment of his career, in July 2017, was with the Inland Empire 66ers of San Bernardino, California, the Class A-Advanced affiliate of the Los Angeles Angels. This allowed Trout to stay closer to the Angels compared to the team's Triple-A affiliate, the Salt Lake Bees.


Umpires at the minor league level are overseen by Minor League Baseball Umpire Development (MiLBUD), which is responsible for the training, evaluation, and recommendation for promotion and retention or release of the umpires. The umpires are evaluated eight times a season by the staff of MiLBUD and receive a ranking at mid-season and the end of each year. Based on performance during the year, an umpire may advance in classification when a position opens in-season or during the off-season. MiLBUD holds an annual Rookie Evaluation Course every year in March to evaluate rookie umpires. Participants are normally the best students from the two professional umpire schools (one owned and operated by the same entity). The top students who pass the evaluation course are recommended for the first openings in lower-level leagues. Any student who wants to work as an umpire must attend a professional umpire training school. Minor League Baseball recognizes two schools for training prospective professional umpires, the Harry Wendelstedt Umpire School and Minor League Baseball Umpire Training Academy, both located in Florida. The Umpire Training Academy is owned and operated by MiLBUD, while the Wendelstedt Umpire School is independently owned by MLB umpire Hunter Wendelstedt. The classes for each school are held for five weeks in January and February. The instructors at these schools are former or present major or minor league umpires. Simply attending one of these schools, however, does not guarantee that the candidate will be recommended to the evaluation course or for openings in lower-level leagues. Generally, less than 20% of students move on to the Rookie Evaluation Course. Before a development program was created, minor league presidents would recruit directly from umpire schools. Umpires were then "sold" from league to league by word of mouth through the various league presidents. The umpire development program first started in 1964, when it was decided that a method of recruitment, training, and development for umpires of both major and minor leagues was needed. The program was founded at baseball's 1964 Winter Meetings in Houston, and it began operating the next year. The program aimed to recruit more athletic, energetic, and dedicated individuals who would also have high morals and integrity standards. In 1968, it was decided that the program needed its own umpire training course, which would be held annually. The first "Umpire Specialization Course" was held in St. Petersburg, Florida, the following year. Presently, the candidates for a job in professional umpiring must meet several requirements in order to be considered. An applicant must have a high school diploma or a G.E.D., must be athletic, and also must have 20/20 vision, although they are permitted to wear glasses or contact lenses. They must also have good communication skills, good reflexes and coordination, and must have trained at one of the two professional umpire schools.


*Patrick T. Powers, 1901–1909 *Michael H. Sexton, 1909–1931 *William G. Bramham, 1932–1946 *George Trautman, 1947–1963 *Phil Piton, 1964–1971 *Hank Peters, 1972–1975 *Bobby Bragan, 1976–1978 *John H. Johnson, 1979–1988 *Sal Artiaga, 1988–1991 *Mike Moore, 1991–2007 *Pat O'Conner, 2008–2020

Television and radio

Minor League Baseball has a national television contract with CBS Sports Network, which airs 10–15 games on Thursday nights. The arrangement began in 2014 and will continue through the 2015 season. For the 2015 season, select MiLB games will be featured on the American Sports Network. Also, many individual teams have contracts with local over-the-air channels. Games are also occasionally simulcast on MLB Network.


MiLB.TV is the minor leagues' official online video streaming service, in the vein of Major League Baseball's MLB.tv. The service currently offers every Triple-A game and select games from the other classifications.


Nearly every minor-league team has its own local radio contract, though unlike their major-league counterparts, these generally consist of only one or two individual stations. Minor League Baseball currently has an arrangement with TuneIn to provide free audio streams of virtually every game.

Independent baseball

Independent leagues are those professional leagues in the United States and Canada not under the purview of organized Minor League Baseball and the Commissioner of Baseball. Independent baseball existed in the early 20th century and has become prominent again since 1993. Leagues operated mostly autonomously before 1902, when the majority joined the NAPBL. From then until 1915, a total of eight new and existing leagues remained independent. Most joined the National Association after one season of independence. Notable exceptions were the California League, which was independent in 1902 and from 1907 to 1909; the United States Baseball League, which folded during its independent 1912 season; and the Colonial League, a National Association Member that went independent in 1915 and then folded. Another independent league, the Federal League, played at a level considered major league from 1914 to 1915. Few independent leagues existed between 1915 and 1993. Major exceptions included the Carolina League and the Quebec-based Provincial League. The Carolina League, based in the North Carolina Piedmont region, gained a reputation as a notorious "outlaw league" during its existence from 1936 to 1938. The Provincial League fielded six teams across Quebec and was independent from 1948 to 1949. Similarly to early 20th-century independent leagues, it joined the National Association in 1950, playing for six more years. Independent leagues saw new growth after 1992, after the new Professional Baseball Agreement in organized baseball instituted more stringent revenue and stadium requirements on members. Over the next eight years, at least 16 independent leagues formed, of which six existed in 2002. Today there are eight active leagues, with four of them acting since 2021 as MLB Partner Leagues.

Leagues and affiliations

Minor leagues

;Triple-A * Triple-A East * Triple-A West ;Double-A * Double-A Central * Double-A Northeast * Double-A South ;High-A * High-A Central * High-A East * High-A West ;Low-A * Low-A East * Low-A Southeast * Low-A West ;Rookie * Arizona League * Gulf Coast League * Dominican Summer League ;Off-season leagues * Arizona Fall League ;Partner leagues * American Association * Atlantic League * Frontier League * Pioneer League ;Independent Leagues * Empire Professional Baseball League * Pacific Association * Pecos League * United Shore League

Major league affiliations

Note: This section has been updated with 2021 affiliate invites announced by MLB teams on December 9, 2020, and with league realignment announced by MLB on February 12, 2021.


Team rosters


MiLBY Awards

The Minor League Baseball Yearly (MiLBY) Awards (formerly "This Year in Minor League Baseball Awards") are given in nine categories. In five categories (Best Starter, Best Hitter, Best Reliever, Best Game, and Best Team), winners are selected in each of the five levels of minor-league baseball (Triple-A, Double-A, Class A-Advanced, Class A, and Class A Short Season). In three categories (Play of the Year, Moment of the Year, and Homer of the Year), one overall winner is chosen for all of minor-league baseball. In the remaining category (Promo of the Year), there are overall winners in each of five subcategories: Best Promotion (of all types), Best Theme Night, Best Giveaway, Best Celebrity Appearance, and Best Miscellaneous Promotion.

Other player awards

* MiLB Topps Minor League Player of the Year Award – also known as the J. G. Taylor Spink Award * MiLB George M. Trautman Awards – Topps Player of the Year in each of the domestic minor leagues * 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

* John H. Johnson President's Award (1974) – given each year, MiLB's top award recognizes "the complete baseball franchise—based on franchise stability, contributions to league stability, contributions to baseball in the community, and promotion of the baseball industry." * Rawlings Woman Executive of the Year (1976) – given each year to a woman in MiLB for exceptional contributions to her club, her league, or baseball. * Warren Giles Award (1984) – given each year to a league president for outstanding service. * King of Baseball (1951) – given annually in recognition of longtime dedication and service to professional baseball. * Larry MacPhail Award (1966) – given annually in recognition of team promotions. * Sheldon "Chief" Bender Award (2008) – given to a person with distinguished service who has been instrumental in player development. * Mike Coolbaugh Award (2008) – given to someone who has shown an outstanding baseball work ethic, knowledge of the game, and skill in mentoring young players on the field. * John H. Moss Community Service Award (2013) – given to a team to recognize outstanding charitable service, support, and leadership. * Charles K. Murphy Patriot Award (2016) – given to an individual or team to recognize outstanding support of and engagement with the United States Armed Forces and veterans.

Top 100 teams

During its centennial celebration in 2001, Minor League Baseball compiled a list of the 100 best minor-league baseball teams of the century.Top 100 Teams
(1901–2001). Minor League Baseball. Retrieved August 19, 2010.

See also

* Korea Baseball Futures League * Eastern League & Western League * History of baseball * Collegiate summer baseball * 2006 Minor League Baseball umpire strike



External links

* {{DEFAULTSORT:Minor League Baseball Category:History of baseball in the United States Category:Sports organizations established in 1901 Category:1901 establishments in the United States Category:Professional sports leagues in the United States Category:Multi-national professional sports leagues