The Vietnam war should be the right answer
<h2>They discovered animals and other things. Maybe this could help</h2>
I guess that it lets us purchase most of the item in the us market, own land, sell our own items, create our own businesses and things like that.
Because the U.S declared that the people of Kansas and Nebraska can vote on to be a slave or free state, in this case northerners rushed there to make it a free state, this whole thing also caused bleeding Kansas