How did demographic and economic changes in american society affect popular debates over american national identity?

The American identity has been shaped and changed due to changes to the demographic shifts and economic changes.

Demographically the US has battled to determine identity in particular to incorporate immigrant culture. Some immigrant cultural pieces have entered into the American identity especially language and food but often other pieces of culture have melded into the "American" culture. White nationalist has been a core identity since the first major immigrant groups came in the 1830s-1840s. 

Economically the US has been built on middle-class to upper-middle class values. The US has been built on hard work and the value of being able to move up in society. This is especially true for white Americans. 

The answer is installation.