Conversation so far:
What did Yip Harburg do in Hollywood?
In Hollywood, Yip Harburg worked with composers Harold Arlen, Vernon Duke, Jerome Kern, Jule Styne, and Burton Lane, and later wrote the lyrics for The Wizard of Oz
Did Yip Harburg work on The Wizard of Oz alone or with others?
According to Ernie Harburg, eleven screenwriters worked on The Wizard of Oz but Yip Harburg pulled it together, wrote his own lines and gave the thing a coherence and unity.
Did Yip Harburg write Over the Rainbow?
Yip Harburg wrote the lyrics for The Wizard of Oz.

Question: What did he do on Broadway?
Self-contained rewrite: What did Yip Harburg do in Broadway?