<span>Early people of the Americas used a combination of animals to further their exploration and expansion into new territories. Some populations used horses and oxen as food sources, and did much of their travel on foot, bringing only what they could carry. Others settled in towns, where food and supplies could be purchased or traded.</span>
A fundamental principle of American government, guaranteed by the Constitution, whereby each branch of the government (executive, judicial, and legislative) has some measure of influence over the other branches and may choose to block procedures of the other branches.
