There is an argument to be made (and I am making it!) that US colonialism started at home, with English colonists (and later the US government) stealing land from indigenous people and breaking treaties. Colonialism in the US context started at home *long* before it spread abroad. First it was Manifest Destiny (combined with the US-Mexico war to take the southwest and California), then it was the Spanish-American war to take the Philippines and Cuba.
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