Atlantic League of Professional Baseball

The Atlantic League of Professional Baseball (ALPB) is a professional independent baseball league based in the United States. It is an official MLB Partner League based in the Mid-Atlantic and Southeastern United States. The Atlantic League's corporate headquarters is located at Clipper Magazine Stadium in Lancaster, Pennsylvania.

The Atlantic League operates in cities not served by Major League Baseball (MLB) or Minor League Baseball (MiLB) teams; most of its teams are within suburbs and exurbs too close to other teams in the organized baseball system to have minor league franchises of their own. The Atlantic League requires cities to have the market for a 4,000 to 7,500-seat ballpark and for the facility to be maintained at or above Triple-A standards. When Atlantic League professionals are signed by MLB clubs, they usually start in their Double-A or Triple-A affiliates.

The league uses a pitch clock and limits the time between innings in an effort to speed up the game. In 2019, the Atlantic League began a three-year partnership with Major League Baseball allowing MLB to implement changes to Atlantic League playing rules, in order to observe the effects of potential future rule changes and equipment. In 2020, the Atlantic League, together with the American Association, the Frontier League, and the Pioneer League, expanded this agreement to become an official MLB Partner League.

The Atlantic League is generally regarded as the most successful and highest level of baseball among independent leagues. The Atlantic League has had more marquee players than any other independent league, including Jose Canseco, Mat Latos, Steve Lombardozzi Jr., Francisco Rodríguez, Chien-Ming Wang, Roger Clemens, Rich Hill, Scott Kazmir, Juan González, and Dontrelle Willis. Two former Atlantic League players are in the National Baseball Hall of Fame and Museum, Tim Raines and Rickey Henderson. Gary Carter, another Hall of Famer, managed in the league. The Atlantic League has had many notable managers and coaches, including Wally Backman, Frank Viola, Tommy John, Sparky Lyle, and Bud Harrelson. The Atlantic League has consistently posted higher per game and per season attendance numbers than other independent circuits including the American Association, Can-Am League, and Frontier League.