Lands acquired after the left the politics of the united states in an unsettled condition. cuban invasion spanish-american war gold rush mexican war gadsden purchase

Mexican War. The Mexican War brought Manifest Destiny almost to a close, Gadsden Purchase would finish it. With all the land though, it also brought the question of slavery back into question. An uneasy balance had been found prior, but the new open land meant that slavery had a place to expand into. The issue had never been completely handled. It was poorly bandaged up and passed along. The legislature would have to grapple once again with the issue. This time though it would lead directly to Civil War. 

An elector in the electoral college.