What is now Class High-A was established as Class A-Advanced in 1990 by subdividing the existingClass A.[1] Class A had been the third-highest level in the minor leagues since 1936 (when it was belowDouble-A and Class A1) and a hierarchy ofTriple-A and Double-A above Class A had been in place since 1946.[2]: 15 In 1963, the three classes below Class A (Classes B, C, and D) were abolished, with leagues at those levels moved into Class A.[2]: 15 In 1965, Class A was subdivided for the first time, with the establishment of lower-levelClass A Short Season leagues.
The 1965 hierarchy was in place for 25 years, until Class A was further subdivided in 1990, with Class A-Advanced becoming the third-highest classification:
Three Class A leagues received the Class A-Advanced designation: theCalifornia League,Carolina League, andFlorida State League.[1] This arrangement continued until 2021, whenMajor League Baseball (MLB) restructured the minor leagues, eliminating Class A Short Season and discontinuing the use of all historical league names within Minor League Baseball.[3] The existing Class A-Advanced leagues were moved to the Class A level and operated under generic names (Low-A West,Low-A East, andLow-A Southeast) during 2021. The Class A-Advanced level was officially renamed as "Class High-A",[4][5] and also operated three leagues during 2021 with generic names:High-A Central,High-A East, andHigh-A West.[6] These three High-A leagues had historically been known as theMidwest League,South Atlantic League, andNorthwest League—the first two had previously operated at the Class A level, while the latter had previously operated at the Class A Short Season level. Following MLB's acquisition of the rights to the names of the historical minor leagues, MLB announced on March 16, 2022, that the leagues would revert to their prior names, effective with the 2022 season.[7]
In January 2023, it was announced thatVeronica Gajownik had been hired to manage theHillsboro Hops, making her the first woman to manage a High-A team.[8]
This sectionis missing information about pre-2021 playoff structure. Please expand the section to include this information. Further details may exist on thetalk page.(September 2024)
The format for the 2024 postseason at High-A will consist of four teams per league in a best-of-three division series, followed by a best-of-three championship series. The four playoff participants per league will be the winners of each division from both halves based on the bestwinning percentage of each half. In the event the same club wins both halves, the club with the next-best winning percentage in the second half will advance.
However, with only six clubs in the Northwest League, the format for the postseason will consist of a single, best-of-five championship series. The two playoff participants will be decided based on the best winning percentage of each half. In the event the same club wins both halves, the club with the next-best winning percentage in the second half will advance.
In the event of any ties, the following tiebreakers will apply in the order below:[9]
Head-to-head record between the clubs in the respective half (if three or more clubs, best winning percentage in games among the clubs).
If the clubs remain tied, best overall winning percentage over the last 20 games.
If the clubs remain tied, best overall winning percentage over an additional game (i.e., the last 21 games, the last 22 games, etc.) until one emerges with a better winning percentage in that span of games.
Midwest League
Northwest League
South Atlantic League
