What was a historical significance of the election of andrew young as mayor of atlanta?

An African American mayor "handed over the keys" of a major city to another African American.

Explanation:

A historical significance of the election of Andrew Young as mayor of Atlanta was that this was the first time an African American mayor "handed over the keys" of a major city to another African American. Andrew Young succeeded Maynard Jackson, who was the first African American to serve as mayor of a major southern city. Thus, both the outgoing mayor and the incoming mayor were African American.