Answer:
El Paso mass shooting is an example from history when Americans were separated by an "us versus them" mentality.
Step-by-step explanation:
One example of "us versus them" mentality of Americans was the El Paso mass shooting.
The agenda of this shooting was to kill as many as "them" i.e Mexicans. This represents an extreme mentality where world is thought of to be divided into an us and a them. During the El Paso mass shooting several poster displayed this mentality in which there was a detailed plan to segregate America into territories by race.