Minor League Baseball Minor league baseball is a hierarchy of professional baseball leagues in the Americas that compete at levels below Major League Baseball ( MLB ) and provide opportunities for player development . All of the minor leagues are operated as independent businesses . Most are members of the umbrella organization known as Minor League Baseball ( MiLB ) , which operates under the Commissioner of Baseball within the scope of organized baseball . Several leagues , known as independent leagues , do not have any official links to Major League Baseball . Except for the Mexican League , teams in the organized minor leagues are generally independently owned and operated but are directly affiliated with one major league team through a standardized Player Development Contract ( PDC ) . These leagues also go by the nicknames the " farm system , " " farm club , " or " farm team ( s ) " because of a joke passed around by major league players in the 1930s when St . Louis Cardinals ' general manager Branch Rickey formalized the system , and teams in small towns were " growing players down on the farm like corn . " Major and Minor League teams may enter into a PDC for a two - or four - year term and may re - affiliate at the expiration of a PDC term , though many relationships are renewed and endure for extended time periods . For example , the Omaha Storm Chasers ( formerly the Omaha Royals ) have been the Triple - A affiliate of the Kansas City Royals since the Royals joined the American League in 1969 , but the Columbus Clippers changed affiliations from the New York Yankees to the Washington Nationals in 2007 and are now affiliated with the Cleveland Indians . A few 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 Atlanta Braves ' affiliates except for the Lynchburg Hillcats . Minor League teams that are owned directly by the major league Club do not have PDCs with each other and are not part of the reaffiliation shuffles that occur every other year . Today , 19 minor baseball leagues operate with 243 member clubs in large , medium , and small towns , as well as the suburbs of major cities , across the United States , Canada , Mexico , the Dominican Republic , and Venezuela . History . The earliest professional baseball association , the National Association 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 midseason . This problem was solved in 1876 with the formation of the National League , with a limited membership which excluded less competitive and financially weaker teams . Professional clubs outside the National League 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 for a championship pennant . The first 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 National League and the American Association , 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 National League and the American Association could only reserve players who had been paid at least $ 1000 . Northwest League teams could reserve players paid merely $ 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 the fiery Ban Johnson decided to challenge the National League ' s position . In 1900 , he changed the name of the league to the American League and vowed to make deals to sign contracts with players who were dissatisfied with the pay and terms of their deals with the National League . This led to a nasty 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 National - American battle , they agreed to form the National Association of Professional Baseball Leagues , called the NAPBL , or NA for short . ( The NA uses the name Minor League Baseball today . ) The purpose of the NA 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 American and National Leagues 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 National and the American . 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 sports writers . News did not travel far in the days before television and radio , 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 . Other than the Pacific Coast League , 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 American and National leagues . 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 American and National leagues 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 league team . This power was leveled primarily at the Baltimore Orioles , then a Triple - A team that had dominated the minors with stars . Current system . Under most circumstances , minor league teams are not owned by Major league clubs , but have affiliation contracts with them . A small number of minor league clubs " are " directly owned by major league clubs , but these are rare . Major league Rule 56 governs the standard terms of a Player Development Contract ( PDC ) which is the standard agreement of association between a minor league team and its major league affiliate . Generally , the parent major league club pays the salaries and benefits of uniformed personnel ( players and coaches ) and bats and balls , while the minor league club pays for in - season travel and other operational expenses . Minor league teams often change their affiliation with major league clubs for a variety of reasons . Sometimes Major or Minor League clubs wish to affiliate with a partner that is geographically closer . In recent years , some MLB clubs have attempted to place as many affiliated teams within their blackout area , to make scouting and player transfers more convenient and to take advantage of the existing fan base , as interest in the parent team builds support for the minor league affiliate and early fan interest in developing minor league players reinforces support for the parent team as " local players " reach the majors . Sometimes a Minor League club wishes to improve the caliber of players its major league affiliate sends to play there . Sometimes a major league club wishes to improve the facility where it will send its developing players . In even - numbered years , any Major or Minor League club with an expiring PDC may notify Major League Baseball or Minor League Baseball , respectively , of its desire to explore a re - affiliation with a different PDC partner . The Major League Baseball and Minor League Baseball offices then send a list of the corresponding Major and Minor League clubs seeking new affiliations , and there is a limited period of time in September within which clubs may agree upon new PDCs . If any are left over after this process , the Major League Baseball and Minor League Baseball offices are empowered to assign Major and Minor League clubs to each other . Going into the 2010 season , the longest continuous link between major league and minor league clubs was the link between the Orioles and their Rookie - level Appalachian League affiliate , the Bluefield Orioles . The teams were affiliated for 53 years , from 1958 through 2010 . Baltimore ended the PDC after the 2010 season . At the start of the 2011 season , the longest continuous affiliations will be two 45 - year links : between the Philadelphia Phillies and their Double - A Eastern League affiliate , the Reading Fightin Phils ; and the one between the Detroit Tigers and their Single - A Florida State League affiliate , the Lakeland Flying Tigers . Both Reading and Lakeland are owned by their parent Major League clubs . The current minor league classification system divides leagues into one of five classes , those being Triple - A ( AAA ) , Double - A ( AA ) , Class A ( Single - A or A ) , Class A Short Season , and Rookie . Furthermore , Class A is further subdivided into Class A and Class A - Advanced ( often called Low - A and High - A , respectively ) . Under the rules governing the affiliated minor leagues ( specifically Major League Baseball Rule 51 ) , Class A Short Season is a separate classification from the other leagues bearing the " Class A " name , despite the similarity in name . Triple - A . This classification currently includes two affiliated leagues : the International League and the Pacific Coast League . The Mexican League is also classed a Triple - A league , though its clubs do not have PDCs with Major League clubs . Both young players and veterans play for Triple - A teams . Teams usually hold many of the remaining 15 players of the 40 - man major league roster whom the major league club has chosen not to play at the major league level . Players at Triple - A on the 40 - man roster can be invited to come up to the major league club once the major league roster expands on September 1 , although teams will usually wait until their affiliates ' playoff runs are over , should they qualify . For teams in contention for a pennant , it gives them fresh players . For those not in contention , it gives them an opportunity to evaluate their second - tier players against major - league competition . Double - A . There are currently three leagues in this classification : Eastern League , Southern League , and the Texas League . Some players will 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 players will be in the majors by the end of the season , as their salaries tend to be higher than those of most prospects . Unlike the major league and the Triple - A level , two of the three Double - A leagues have their season divided into two parts , the Eastern League being the exception . One team may clinch a spot in the playoffs by winning the division in first half of the season . The teams ' records are then cleared and another team will also clinch a playoff slot during the second half . Wild cards are used to fill out the remaining teams . Usually , four teams qualify for the league playoffs . This system is used at the Class A level as well . Class A . Class A is a classification comprising two sub - classifications : Class A - Advanced and Class A . Players usually have less experience or have particular issues to work out ; pitching control and batting consistency are the two most frequent reasons for a player to be assigned to Class A baseball . Class A - Advanced . One level below Double - A , the California League , Florida State League , and the Carolina League play at the Class A - Advanced level . This is often a second or third promotion for a minor league player , although a few high first - round draftees , particularly those with college experience , will begin at this level . These leagues play a complete season like Triple - A and Double - A , April through early September . Many of these teams , especially in the Florida State League , are owned by major league parent clubs and use their spring training complexes . Class A . Slightly below Class A - Advanced are the full season Class - A leagues , the South Atlantic League and Midwest League . These leagues are a mix of players moving up from the Short - Season A and Rookie leagues , as well as the occasional experienced first - year player . These leagues play a full , 140 game schedule , which runs from the first week of April through the first week of September . Class A - Short Season . Class A - Short Season , despite sharing the " Class A " designation , is , in fact , a separate classification from Class A . Short Season A teams are slightly more limited than Class A teams with respect to player age and years of experience in professional baseball . As the name implies , these leagues play a shortened season ( roughly 75 games ) , starting in mid - June and ending in early September , with only a few off - days during the season . There are two short - season leagues , the New York – Penn League and Northwest League . They contain the highest level short - season affiliates for 22 MLB organizations . The affiliates of the remaining eight MLB clubs have their highest level short - season affiliate in either the Appalachian or Pioneer Leagues , which are officially classified as " Rookie " level leagues . The late start of the season is designed to allow college players to complete their college seasons in the Spring , then be drafted , signed , and immediately placed in a competitive league ( The MLB First Year Player Draft begins on the first Monday in June ) . Players in Short Season leagues are a mixture of newly signed draftees and second - year pros who weren ' t ready to move on , or for whom there was not space at a higher level to move up . Second - year pros tend to be assigned to Extended Spring Training in Florida or Arizona during April and May before reporting to their short - season leagues . For many players , this is the first time they have ever used wooden baseball bat s , as aluminum bats are most common in the amateur game . Players are permitted to use certain approved composite bats at this classification to help them make the transition from aluminum to wood bats . This is also often the first time they have played every day for a prolonged basis , as amateur competitions typically regulate the number of games played in a week . Rookie . Leagues in the Rookie classification play a shortened season , similar to ( but slightly shorter than ) the Class - A Short - Season leagues , starting in mid - June and ending in late August or early September . This lowest level of minor league baseball consists of four domestic leagues , the Appalachian League , Pioneer League , Arizona League , and Gulf Coast League , as well as two foreign - based leagues , the Dominican Summer League , and Venezuelan Summer League . Rookie leagues ( Gulf Coast and Arizona ) play a 60 - game schedule , while Advanced Rookie leagues ( Appalachian and Pioneer ) play between 67 and 75 games with fewer days off . The Appalachian and Pioneer leagues are actually hybrid leagues ; while officially classed as " Rookie " leagues , eight major league teams have their highest - class short season teams in those leagues . These eight teams also maintain Rookie - level teams in other leagues as well . The Gulf Coast and Arizona leagues are informally known as " complex " leagues , nicknamed for the minor - league complexes where most games in those leagues are played . Variations in the system . There are variations to the farm system ' s classes that should be noted : Reorganization of 1963 . The current minor league structure is largely based on a significant reorganization that occurred before the season , which was caused by the club and league contraction of the 1950s and early 1960s . In , 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 , only 15 leagues survived in the United States and Canada . Previous structure ( 1946 – 1962 ) . In , the Triple - A classification was created and it became the highest level of the minors , which formerly was called Double - A . The two Class A1 circuits , the Texas League and the Southern Association , were then designated Double - A , now two rungs below MLB . Before 1963 , the Class A level was a middle - to higher - rung classification . In 1946 , Class A consisted of the Eastern League and the original South Atlantic or " Sally " League , and it would soon include the Western League ( 1947 – 1958 ) , the Central League ( 1948 – 1951 ) , and the Western International League ( 1952 – 1954 ) , which would become the Class B Northwest League in 1955 . The lower levels of the minors were ranked Classes B through D in descending order . With the exception of the 1952 – 1957 Open Classification experiment for the Pacific Coast League , this structure would remain intact through . ( see " Defunct levels , " below ) The 1963 classification realignment . During the 1962 – 1963 offseason , the two remaining Triple - A leagues ( the International and Pacific Coast leagues ) absorbed the four surviving franchises from the defunct American Association . Meanwhile , at the Double - A level and below there were even more significant changes : 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 . Defunct levels . Open . The Pacific Coast League , from 1952 – 1957 , was the only minor league to obtain this classification . At this time , the major leagues only extended as far west as St . Louis and as far south as Washington , DC . 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 classification 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 . The open classification no longer exists in the major league rules . Class A1 . The forerunner to the modern Double - A classification , the A1 level existed from 1936 through 1945 . In , two Class A circuits , the Texas League and the Southern Association , were upgraded to 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 . Ten years later , after World War II , with the minor leagues poised for unprecedented growth , classification terminology was changed . Beginning in , the three Double - A leagues ( the American Association and International and Pacific Coast leagues ) joined a new classification , Triple - A , and the two A1 leagues became known as Double - A . Class B , C and D . Until 1963 , there were also Class B , C , and D leagues ( and , for half a season , one E league ) . The Class D of that day 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 C . The Class E level existed briefly in 1943 in the form of the Twin Ports League . It folded July 13 after six weeks of operation . Players . Only 25 of the players on a Major League Baseball team ' s 40 - man major league reserve list may be active for the major league club , except from September 1 to the end of the regular season when teams are allowed to expand their game - day rosters to 40 players . The remaining 15 players are generally either on the disabled list or play at some level of the minor leagues ( usually at the AAA or AA level ) . Players on the 40 - man reserve list are eligible for membership in the Major League Baseball Players Association . The 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 evaluation of players is a constantly ongoing process . The Director of Player Development and his managers will 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 will get a second or third look from the major league scouts if they turn their career around in the independent leagues . Even though minor league players are paid considerably less than their major league counterparts , they are nevertheless paid for their services and are thus considered professional athletes . Baseball cards refer to " pro record " and " pro seasons " as including both major and minor leagues . For this reason , minor league players generally consider it an insult when someone asks when they ' re going to " get to the pros " . More accurately , a player ' s aim is to reach " The Show " or the " big leagues . " In addition , a major league player on the disabled list may be sent to a minor league club for a " rehabilitation " assignment , allowing the player to face live competition ( though not Major League level ) as a means of working his way back into the regular lineup , prior to being returned to the team ' s active roster . Umpires . The umpires are the people charged with officiating the game , including beginning and ending the game , enforcing the rules of the game and the grounds , making judgment calls on plays , and handling the disciplinary actions . The body responsible for any action related to the training , evaluation , and recommendation for promotion and retention or release of the umpires is the Professional Baseball Umpire Corp , which is an owned subsidiary of the National Association of Professional Baseball Leagues . The umpires are evaluated eight times a season by the staff of the PBUC , 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 the following season . PBUC holds an annual Evaluation Course every year in March to evaluate rookie umpires . Participants are normally the best students from the two professional umpire schools owned and operated by the same entity . The top students who pass the Evaluation Course are recommended for the first openings in the Rookie and Short - A leagues . Any student who wants to work as an umpire must attend a professional umpire training school . The PBUC recognizes two schools for training prospective professional umpires , the Harry Wendelstedt Umpire School and The Umpire School , both located in Florida . The Umpire School is owned and operated by PBUC , while Wendelstedt 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 also be recommended either to the Evaluation Course or to the openings in the Rookie or Short - Season A league . Before the umpire development program was created , the Minor League presidents would recruit umpires directly from the 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 Umpire Development 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 each year . 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 , no matter if they 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 . Minor League Baseball / NAPBL . Minor League Baseball , formerly the National Association of Professional Baseball Leagues and also known in the past as NAPBL , National Baseball Association , and NA , is the organization which oversees the governing and organization of minor league baseball in North America . The NAPBL formed in 1901 as a reaction to the warfare going on between the National League and the American League . The presidents of the other professional baseball leagues then in existence were concerned that the two " major leagues " and their continuing pirating of players and even whole teams were a threat to the existence of professional baseball in the United States and Canada . At the time , the National and American Leagues were not seen as " major leagues " , but only as leagues which existed in larger cities . Led by Patrick T . Powers , then - president of the Eastern League , the larger minor leagues then in existence banded together to control their own fates . Powers ' idea was that , instead of going head - to - head with the National and American Leagues , the other leagues should set standard rules for officiating , player drafts , contracts , and location of teams . Fourteen leagues ( the Eastern League , Western League , New England League , New York State League , Pacific Northwest League , Southern Association , Three - I League , Carolina League , Connecticut League , Cotton States League , Iowa - South Dakota League , Michigan State League , Missouri Valley League and Texas League ) signed the agreement to begin play under the new rules effective with the 1902 season . Many leagues refused to join , fearing that the creation of the NA was just an attempt at forming another " major " league , and that its rules and territorial limits would interfere with their independence . When that fear failed to materialize , however , more and more leagues joined the NA until , within a few years , it consisted of thirty - five leagues . Patrick Powers resigned his presidency of the NA in 1909 in order to concentrate on his private business interests . The Association managed to maintain its original purpose for about twenty years , but during the Great Depression , many leagues began to fold , and the Association needed to look for more funding in order to keep minor league baseball going . This funding came from the same major league teams which the NA had been created to protect itself from . Starting in 1931 , major league teams began affiliation agreements with minor league teams . Branch Rickey , president of the St . Louis Cardinals , was the architect of the system which exists today , in which most minor league teams are affiliates of major league teams , supplying the Majors with development of younger players in exchange for financial support from the major league teams with which they are affiliated . Because so many professional players went to fight during World War II , the number of teams and leagues decreased even more until the end of the war . From 1945 , when there were only twelve leagues left in the NA , there were fifty - nine in 1949 . That number has decreased until , today , there are seventeen . In 1999 , the NAPBL formally changed its name to Minor League Baseball , which governs the minor league system , although there are several independent leagues which do not fall under the group ' s aegis . Awards . 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 – Full Season , 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 . Top 100 teams . During its centennial celebration in 2001 , Minor League Baseball compiled a list of the one - hundred best minor - league baseball teams of the century .