As of the 2022 season, the minor league system is divided into four classes: Triple-A (AAA), Double-A (AA), High-A (A+), and Single-A (A). See more

19th century
The earliest classifications used in the minor leagues began circa 1890, for teams that were party to the National Agreement of 1883. The … See more

Minor League Baseball was governed through a centralized office until the restructuring of the minor leagues in 2021, with Major League Baseball itself now handling "all issues … See more

The earliest professional baseball league, the National Association of Professional Base Ball Players of 1871 to 1875, commonly referred to as the National Association, … See more

Major league clubs may only use players who are on the team's major league active roster in games; players on the active roster are selected from a 40-man major league reserve list … See more

Umpires at the minor league level are overseen by Minor League Baseball Umpire Development (MiLBUD), which is responsible for the training, evaluation, and recommendation … See more

Teams in the affiliated minor leagues are generally independently owned and operated, and are directly affiliated with one major league … See more