The Subway Series is a series of Major League Baseball (MLB) rivalry games played between the two teams based in New York City, the Yankees and the Mets. Previously, this applied to the Giants and Dodgers as well, before they moved out of New York City. Every historic and current venue for such games has been accessible via the New York City Subway, hence the name of the series.
The term's historic usage has been in reference to World Series games played between the city's teams. The New York Yankees have appeared in all Subway Series games as they have been the only American League (AL) team based in the city, and have compiled an 11–3 all-time series record in the 14 championship Subway Series.
Since 1997, the term Subway Series has been applied to interleague play during the regular season between the Yankees and New York City's National League (NL) team: the New York Mets. The Mets and Yankees also played each other in the 2000 World Series, in which the Yankees won.
19th century Trolley Series
Although organized games between all-stars from New York teams against all-stars from Brooklyn teams date back to the 1850s, the first actual New York-Brooklyn "World Championship Series" occurred in 1889, a full nine years before Brooklyn was incorporated into the City of New York by the Greater New York Act of 1898, when the New York Giants squared off against (and defeated) the Brooklyn Bridegrooms, also called the "Trolley Dodgers", of the American Association. The following season, Brooklyn withdrew from the Association and joined the League, setting the stage for many future intra-city competitions.
Some might argue that the 1889 Series would qualify as a "Trolley Series", but would not qualify as a Subway Series since New York's subway did not open until 1904.
The 1906 World Series between the Chicago Cubs and the Chicago White Sox is also loosely referred to as a Subway Series, though the term Crosstown Series is more commonly used. The term is also inaccurate, since Chicago had surface systems from 1892 till the building of the State Street Subway in 1943.
Early and mid-20th century Subway Series
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. The 155th Street elevated and subway stations, the 161st Street station, and the Prospect Park respectively, served the ballparks. (New York's subway and elevated systems—the IRT, BRT/BMT, and IND—were in competition with each other until 1940.)
In the case of the World Series contests listed, the entire Series could be attended by using the subway. The date of the first usage of the term "Subway Series" is uncertain. The term "Nickel Series" (a nickel was the old subway fare) appeared in newspapers by 1927, and "Subway Series" appeared by 1928. "Subway Series" was clearly already a familiar concept by 1934, as discussed in this article about that year's All-Star Game to be held in New York, discussing the "subway series" possibility for the Giants and Yankees. (Ultimately, no New York team made it to the 1934 post-season.).
Yankees–Giants
The 1921 and 1922 match-ups were played in a single ballpark, as both the Giants and Yankees then played at the Polo Grounds. The Giants won both of these World Series against the Yankees, the first two Subway Series played. Despite cordial relations just a few years before when the Yankees allowed the Giants to share their home at Hilltop Park for a year in 1911 and the Giants more than returning the favor in kind by sharing Polo Grounds with the Yankees since 1913, the Yankees were issued an eviction notice in mid-1920 ending their lease after the 1922 season. The Yankees opened their new ballpark in 1923. 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. Their new home would host the Yankees' first of 11 Subway World Series victories that year and first of an unprecedented 26 World Series until the stadium closed in 2008.
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.