NAPBL/MiLB/Player Development League

The affiliated minor leagues were officially annointed the National Association of Professional Baseball Leagues in late 1901, bringing together under one umbrella 14 leagues comprised of 96 teams. Ironically, the original intent was to preserve the independence of the minor leagues in response to the birth of the American League and the turf wars that resulted between the Majors and the minors.

In 1903 with the nascent AL now an equal and accepted partner of the National League, further rules were established to compensate the minor league teams (which weren’t yet called “minor leagues”) for players signed away by Major League clubs.

True affiliation with Major League Baseball was famously invented by Branch Rickey in the 1930s, and the modern minor league farm system was born.

What became known as MiLB saw several eras of fundamental change, most notably the explosion of teams and leagues in the post-WWII years; the great attendance drop-off during the 1950s and the resulting contraction ushered in by the westward expansion of MLB and the advent of televised games; a restructuring and renaming of the classifications in 1963; and the final expiration of the Basic Agreement in September of 2020, after which Major League Baseball assumed complete control, reorganized the affiliated minor league structure including the elimination of the individual league offices, and renamed Minor League Baseball to Player Development League.

A more detailed account of the organization’s history can be found here.