Answer:
This process of enlargement of the American territory was called “westward march” and occurred in two ways: through diplomacy or buying and war.
This was very motivated by the economic problems of the 1830s - 1840s. So did the so-called 1837 Panic in the United States when a banking bubble burst. Banks stopped making payments in gold and silver coins. It was six years of depression, with the collapse of financial institutions and high unemployment and the famous westward race.
