I truly don’t know the answer but I go on safari and look it up LOL
One would be technology, another one would be labor force, and supply and demand also played a major factor.
Americans were afraid that new immigrants would take their jobs during the 1880's. During the late 19th century, the US was constantly expanding by building more railroads, roads, etc. that relied on labor. Businesses often hired the cheapest labor they could since there was no minimum wage laws yet. Often times, immigrants would take a lower pay rate than American citizens.
This fear spread like wildfire and caused an increased amount of nativism. Nativism is the belief that the wants/need of native born citizens should be a priority over those of immigrants.
The word “imperialism” is widely used as an emotive—and more rarely
as a theoretical—term to denote specific forms of aggressive behavior on
the part of certain states against others; the concept refers primarily
to attempts to establish or retain formal sovereignty over subordinate
political societies, but it is also often equated with the exercise of any form of political control or influence by one political community over another.
hope this helps :)