<Li> 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 an umbrella circuit, the 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 . </Li> <Li> Class A: In 1965, the Class A--Short Season designation was created, and the Northern and Northwest loops moved from "full season" Class A into the new classification (with the New York--Penn League following in 1967). 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 . </Li> <Li> 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, an Arizona - based counterpart to the Gulf Coast League, the Arizona League, made its debut in minor league baseball, and it continues to operate as a Rookie - level league for MLB teams with spring training facilities based in that state . </Li> <Li> Failed start - up leagues: During the 1970s, three "official" minor leagues attempted unsuccessfully to revive unaffiliated baseball 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 . </Li>

What are the classes of minor league baseball