Class High-A was established as a classification level within
Class A.[1] Class A had been the third-highest level in the minor leagues since 1936 (when it was below Double-A and Class A1) and a hierarchy of Triple-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-level Class 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:
Triple-A
Double-A
Class A-Advanced
Class A ("Full-Season A")
Class A Short Season ("Short-Season A")
Rookie league
Three leagues, each previously Class A, received the Class A-Advanced designation: the
High-A West.[6] These three High-A leagues had historically been known as the Midwest League, South Atlantic League, and Northwest 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 that Veronica Gajownik had been hired to manage the Hillsboro Hops, making her the first woman to manage a High-A team.[8]
This section needs expansion with: playoff structure prior to the 2021 re-org. You can help by adding to it. (June 2021)
On June 30, 2021, Minor League Baseball announced that the top two teams in each league (based on full-season winning percentage, and regardless of division) would meet in a best-of-five postseason series to determine league champions.[9]