A key factor of the empires the United States and European countries built in the late 1800s was:

Chauvinism is an exaggerated belief that one’s own nation is superior to others. In the late 1800s, this belief helped justify U.S. and European expansion and control over other peoples. Nationalism and patriotism can encourage pride in one’s country, but chauvinism more specifically expresses the superiority used to support empire-building.

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