The United States. As the main cause of this war was the westward expansion of the United States. That American ideal of “Manifest Destiny.” That it was their god given right to expand westward. At the time before the period of the Mexican-American war, people believed they could conquer people already living on the land and take it for the United States.
The Industrial Revolution marked a period of development in the latter half of the 18th century that transformed largely rural, agrarian societies in Europe and America into industrialized, urban ones.