Conversation so far:
What did Yip Harburg do in Hollywood?
Harburg and Gorney were offered a contract with Paramount: in Hollywood, Harburg worked with composers and later wrote the lyrics for The Wizard of Oz's Over the Rainbow.“
What year did Yip Harburg write for Wizard of Oz?
The Wizard of Oz writing began when Walt Disney's Snow White and the Seven Dwarfs showed that films adapted from popular children's stories and fairytale folklore could still be successful.
What was names of some broadway shows Yip Harburg produced?
In the 1940s, Yip Harburg wrote a series of book musicals with social messages, including the successful Bloomer Girl and Finian's Rainbow.
Did Yip Harburg actually act or was part of the shows?
Yip Harburg did not act.

Question: What year did he start writing for Hollywood or Broadway?
Self-contained rewrite: What year did Yip Harburg start writing for Hollywood or Broadway?