What caused an increase in suburbs in the 1920s?

In the 1920s, U.S. suburban growth surpassed urban growth for the first time (Weeks 1981). Economic factors during the Great Depression caused the growth of suburbs to decline drastically. ... In fact, economic factors have helped constrain suburban growth that has been driven by other factors, such as race.

Explanation:

i think it was because of how protected egyptian civilization was was which allowed them to evolve without much outside influence.

b - those executed came from every social and economic class