As the result of Mexican American war, the treaty of Guadalupe Hidalgo, a peace treaty was signed on 2 February 1848 at Villa De Guadalupe Hidalgo. This treaty added 525,000 square miles to United States territory and establishes the Rio Grande river as the US-Mexican border. However, Guadalupe Hidalgo is the oldest treaty between an America and Mexico and which is still in force.
The short answer is: "to a great extent". The entire plan of the Federalists was to create a strong central government instead of having many autonomous states. Of course this occasionally went against national unity in the sense that some people were opposed to this plan, but in general they favored unity.
The resulting outcry across the United States led to a number of antiwar demonstrations—it was at one of these demonstrations that the National Guard shot four protesters at Kent State.
