interleague

Interleague refers to interaction, competition, or collaboration between entities that belong to different leagues, associations, or regions. The term is most commonly used in sports to describe games or contests between teams from separate leagues or conferences, but it can also apply to broadcast rights, tournaments, or joint ventures involving different organizations.

In Major League Baseball, interleague play denotes the regular-season games between American League and National League teams. It was introduced in 1997 as part of an expansion of the schedule and has since become a standard feature of the season. Interleague games are scheduled within the overarching season, with some seasons emphasizing certain rivalries or hosting events such as annual interleague weekends. While results count toward a team's league record, the two leagues remain separate in terms of pennants and postseason qualification.

High-profile interleague matchups have included cross-league rivalries such as the Subway Series (New York Yankees vs New York Mets), the Freeway Series (Los Angeles Angels vs Los Angeles Dodgers), and the Crosstown Classic (Chicago White Sox vs Chicago Cubs). Interleague play has been both popular with fans and criticized by others who argue it disrupts traditional league balance or reduces the competitive tension of intra-league games.

Outside MLB, interleague play or interleague competition is used to describe cross-league matchups in other sports and formats, including international club competitions, tournament formats, or exhibition matches that pair teams from different leagues, associations, or national systems. The concept supports exposure to diverse styles of play and can broaden fan bases and media interest.