The term historically refers to World Series games played between the city's teams.

The Yankees have appeared in all Subway Series games as they have been the only American League (AL) team based in the city.

[1] The New York Giants squared off against (and defeated) the Brooklyn Bridegrooms, also called the "Trolley Dodgers", of the American Association.

[1] The following season, Brooklyn withdrew from the Association and joined the League, setting the stage for many future intra-city competitions.

[1] By the 1920s, the subway had become an important form of public transport in the city and provided a convenient form of travel between the three city ballparks: the Polo Grounds, in upper Manhattan; Yankee Stadium, in the Bronx; and Ebbets Field in Brooklyn.

Fortunes changed immediately for the Yankees as they defeated the Giants this time in the third straight year of World Series competition between the two teams.

[4] The venues for the 1923, 1936, 1937, and 1951 World Series—the Polo Grounds and the old Yankee Stadium—were a short walk apart across the Macombs Dam Bridge over the Harlem River.

Multiple Hall of Famers took part in these contests between the "Bronx Bombers" and "Dem Bums from Brooklyn" and the games involved numerous achievements including Jackie Robinson breaking the color barrier as the first African-American baseball player in the World Series and Don Larsen's performance in pitching the only perfect game in post-season history.

Before New York's two National League teams left the city, the Yankees and Giants (from 1946‍–‍1950, 1955) and Yankees and Dodgers (1951‍–‍1954, 1957) played an annual midseason exhibition game called the Mayor's Trophy Game to benefit sandlot baseball in New York City.

[citation needed] After dwindling interest and public bickering between the owners of both teams, the Mayor's Trophy Game was discontinued following the 1983 season.

[citation needed] That being said, the term, "Subway Series" is only generally applied to Major League Baseball.

The rivalry has included heated moments such as the Roger Clemens and Mike Piazza feud.

Clemens, of the Yankees, threw part of a broken bat at Piazza, of the Mets, after a hit.

On June 12, 2009 Luis Castillo of the Mets dropped a popup hit by Alex Rodriguez giving the Yankees a win in the series.

[25] The Yankees won four games to one and celebrated their 26th championship in front of Mets fans at Shea Stadium.