In the late 1800s, sheet music publishing became more and more centralized to New York, in particular to the area of 28th Street between Broadway and Fifth Avenue, near Union Square.
In the summer, with windows open, pedestrians could hear the tinny tintinnabulation of cheap pianos up and down the street as songwriters hoping to be the next Irving Berlin or Cole Porter pounded out song after disposable song for the entertainment trade.
Eventually Tin Pan Alley shifted to West 28th Street and finally to offices in and around the Brill Building, on Broadway near 50th.
In the 1960s, most rock and pop performers chose to write their own songs, forcing the last crop of professional songwriters, like Carole King, Barry Mann, Neil Diamond, and Neil Sedaka, into writing TV theme songs and commercials or becoming performers in their own right.
The beginning of Tin Pan Alley is usually dated to about 1885, when a number of music publishers set up shop in the same district of Manhattan.