Take Me Out to the Ball Game

"'Take Me Out to the Ball Game' is a 1908 Tin Pan Alley song by Jack Norworth and Albert Von Tilzer which has become the unofficial anthem of baseball, although neither of its authors had attended a game prior to writing the song. The song (chorus only) is traditionally sung during the seventh-inning stretch of a baseball game. ... Jack Norworth, while riding a subway train, was inspired by a sign that said 'Baseball Today — Polo Grounds'. In the song, Katie's (and later Nelly's) beau calls to ask her out to see a show. She accepts the date, but only if her date will take her out to the ballgame. The words were set to music by Albert Von Tilzer, (Norworth and Von Tilzer finally saw their first Major League Baseball games 32 and 20 years later, respectively). The song was first sung by Norworth's then-wife Nora Bayes and popularized by many other vaudeville acts."
Wikipedia

One, Two, Three: A Century of Baseball’s Anthem
"... The story goes that Norworth penned the lyrics one day while riding one of Manhattan’s new subway trains north toward the Polo Grounds. He remembered seeing a sign advertising that day’s game and pulling out a pencil and paper to scribble down a set of lyrics, which Von Tilzer would later pair with a tune he had composed. (The original manuscript is part of the Hall of Fame Library’s collection.) The song was not immediately popular at ballparks, surprisingly enough. In fact, the first known time it was performed in a ballpark was in 1934, almost 30 years after it was written. But it was a big hit in 1908, selling millions of copies of sheet music and 'Edison Wax Cylinder' recordings. Its initial popularity was due to a set of 'lantern slides' shot at the Polo Grounds to promote the song. The slides tell the story of Katie Casey, the fictional protagonist of the songs’ two rarely-heard verses, who implores her beau to take her out to the ball game."
Baseball Hall

YouTube: "Take Me Out To the Ball Game", September 1908