Official government order that limits trade with a nation

Declaration of war

Explanation:

If the trade is limited to punish a nation, then it is likely an act of war.

I.E. America's cut in oil trade with Japan during WW2 because Japan allied with Germany, which led to Japan attacking America out of desperation/anger

here are some major conflicts i found. maybe pick one and do more research on it. (cause i ain't writing 6 paragraphs)

in 1877, the nez perce war took place.

1881 - president james garfield was assassinated.

1882 - the chinese exclusion act was passed.

1883 - a decision in the civil rights cases legalized racial segregation in the united states.

1887 - the dawes act was passed.

1893 - the panic of 1893 took place. (what a creative name)

and there are probably other topics you can find if you just search up "united states timeline," or "conflicts in the 19th century for america."

then once you find a topic you like find out how it affected the people of america and what not. (sorry if this feels a bit short changed, history was and never will be one of my strong topics)

by 1880, germany had more rail lines than great britain and russia.