List of affiliated Minor League Baseball leagues

This is a list of the leagues constituting Minor League Baseball from 1963 until its reorganization in 2021 as the Professional Development League.

Leagues affiliated with Minor League Baseball

AAA (Triple-A) Leagues

• International League (1946-2019, AA 1912-1945, known as Eastern League 1902-1911)
• Mexican League (1967-present, AA 1955-1966) note that the league was unaffected by the 2021 reorganization
• Pacific Coast League (1946-1951 and 1958-2019, Open classification 1952-1957, AA 1912-1945, A 1904-1911)

AA (Double-A) Leagues

• Eastern League (1963-2019, A 1938-1962, New York-Pennsylvania League 1923-1937)
• Southern League (1964-2019, known as South Atlantic League 1936-1942 and 1946-1963)
• Texas League (1946-2019, A 1921-1942, B 1911-1920, C 1904-1905 and 1907-1910, D 1902-1903 and 1906

A (Single-A) Leagues

• California League (1963-2019, C 1941-1942 and 1946-1962)
• Carolina League (1963-2019, B 1949-1962, C 1945-1948)
• Florida State League (1963-2019, D 1936-1941 and 1946-1962)
• Midwest League (1963-2019, D 1956-1962; known as Illinois State League, 1947-1948 and Mississippi-Ohio Valley League, 1949-1955)
• New York-Pennsylvania League (1963-2019, D 1957-1962, known as Pennsylvania-Ontario-New York League 1939-1956)
• Northern League (1963-1971), C, 1941-1942 and 1946-1962, D 1946-1940)
• Northwest League (1963-2019, B 1955-1962, known as Western International League 1937-1942 and 1946-1951)
• South Atlantic League (1980-2019); known as Western Carolinas League 1963-1979 and Western Carolina League 1960-1962)

Rookie Leagues

• Appalachian League (1963-2019, D 1957-1962)
• Arizona League (1988-2019)
• Dominican Summer League (1985-present) note that the league was unaffected by the 2021 reorganization
• Gulf Coast League (1966-2019)
• Pioneer League (1963-2019, C 1946-1962)
• Venezuelan Summer League (1997-2015)