What were some technological and demographic changes that enabled the United States to go through a process of rapid urbanization beginning in the 1920s? 

 What were some reactionary movements that developed as a (negative) response to immigration and urbanization in the United States?  2022 latest answers

Conversely, how did the growth of cities affect the development of a common American culture during this time?

 Explain how some of these urban cultural developments are still a part of American society today. (Be specific and back your assertions with evidence.)