The supply of any non-renewable natural resource such as oil is limited. Other natural resources such as cotton or peanuts may be limited during one growing season, but renewable over a period of years. This affects price and availability. Human resources are also often limited because the number of people possessing a certain skill may be limited, or funds to pay laborers may be limited. The U.S. Constitution enacted a system of federalism in which the power to govern is divided between national and state governments.
Some authority is exclusively that of the nation and some authority is vested with the states.
Other authority is shared by the two. These powers are divided among the three branches of national government. The legislative branch has the power to tax, to regulate commerce, to define the requirements of naturalization, to coin money, and to declare war, among others. The executive branch can command the army, navy and state militias, and appoint and receive foreign ambassadors. The judicial branch decides lawsuits between states and cases that impact foreign ambassadors.