Question

why was the united states justified in their imperialistic policies of the late 1800s and the early 1900s ? why did the united states shift from expanding internally towards foreign expansion in the late 1800s and early 1900s?

Answer 1

It was an attempt to maintain economic stability. The US was suffering from a 'crisis of overproduction'... Factories flooded domestic markets with too many goods, and needed foreign outlets for the surplus. If no new foreign markets were found, they'd have to cut down on production, which would lead to an increase in unemployment.