A (short-season)

While most class A leagues play a schedule around 140 games long, Short-season Class A leagues started only after that year's amateur draft, held at the beginning of June, with a season lasting about 75 contests. The arrangement was to allow teams to sign the players they had just drafted, and switch them around in the organization without having to disrupt a bunch of teams whose season was already under way.

Before the great Minor League Reorganization that preceded the 2021 season, there were only two such leagues in existence at the Single-A level (there were more at the Rookie level) - the New York-Penn League and Northwest League. The leagues were usually stocked with recently drafted college players, with occasional top high school prospects (usually sent to Rookie leagues instead) or players who have some limited professional experience. With the move of the amateur draft to mid-July, the raison d'être of the two leagues disappeared, and with MLB wanting to cut the costs associated with the minor league structure, they were obvious candidates to be eliminated. A few of their teams managed to survive by being transferred to a higher classification, but most of them either joined an independent league or a summer collegiate league.