The league has played at the Double-A level since 1963, and consists primarily of teams located in the Northeastern United States.

The league has had teams in a total of 52 different cities, located in 12 different states and two Canadian provinces.

The league expanded to 12 teams in 1999 with the addition of the Altoona Curve and the Erie SeaWolves.

[17] The Binghamton Triplets have won 10 championships, the most among all teams in the league, followed by the Elmira Colonels/Pioneers/Royals (8) and the Scranton Miners/Red Sox (7).

Among active franchises, the Akron Aeros/RubberDucks and Harrisburg Senators have each won 6 championships, the most in the league, followed by the Reading Fightin Phils (4).