Subway Series lacking a definition

I came from a family that was deeply into sports, especially baseball. I was not much for memorizing stats or going nuts over the game, even though I like to play. I must have heard the phrase Subway Series at least a hundred times in the past few days but there was no definition ever mentioned. It seems like if you don’t know what it is, you will never know. This truly discriminates against the baseball challenged.

Two teams from the same city playing each other. They alternate between the 2 teams’ home stadiums; with Mets vs. Yankees, they could ride the subway to the away games.

Slight nit pick. Oakland vs San Fran is a subway series even though they are two different cities.

Hijack why does such a puny city like Oakland have a team. They are the Green Bay (also a puny city) of Baseball

By the way, just so you know, the Yankees will win.