The United States Army overwhelmed the Mexican forces, which lead to a huge chunk of territory being part of the terms of surrender. Much of California, New Mexico, Arizona, and I believe parts of Nevada, and certainly Texas (although most Texans alread considered themselves independent of Mexico) were part of the territory during the negotiations between both country's. You should check further to see if the territory extended even more northward.
As a result of this newly acquired territory, North and South would endlessly argue over how each state should be admitted into the union, free or slave. This was the poisonous bone of contention that would directly lead both sides into the American Civil War.
As a result of this newly acquired territory, North and South would endlessly argue over how each state should be admitted into the union, free or slave. This was the poisonous bone of contention that would directly lead both sides into the American Civil War.