Conversation so far:
What is Tin Pan Alley?
The name originally referred to a specific place: West 28th Street between Fifth and Sixth Avenues in the Flower District of Manhattan.
What did George Gershwin do in Tin Pan Alley?
George Gershwin found his first job as a song plugger.
What is a song plugger?
A song plugger or song demonstrator was a vocalist or piano player employed in the early 20th century to sell new sheet music.
Did George Gershwin do broadway shows?
George Gershwin began his career as a song plugger but soon started composing Broadway theater works with Buddy DeSylva and his brother Ira Gershwin.

Question: Were they popular?
Self-contained rewrite: Were the broadway shows composed by George Gershwin popular?