The American Association, Frontier League, Atlantic League and Pioneer League are independent baseball leagues that have been designated as Partner Leagues of MLB.
These leagues will collaborate with MLB on initiatives to provide organized baseball to communities throughout the United States and Canada while working to expand the geographic reach of the game.
Previously, the Pioneer League was a Minor League Baseball affiliate. It became an independent league as part of MLB’s reorganization of MiLB in November 2020. The American Association, Frontier League and Atlantic League were already independent before being designated as Partner Leagues.
Meanwhile, five former MiLB affiliated teams -- the Mahoning Valley Scrappers, State College Spikes, Trenton Thunder, West Virginia Black Bears and Williamsport Crosscutters -- have been announced as founding members of the MLB Draft League, which will give eligible prospects a chance to showcase their abilities and gain exposure prior to the MLB Draft. Also, the Appalachian League has been converted from an MiLB affiliate into a collegiate wood-bat summer league.