The United States has 50 states, one federal district and numerous territories. Its political system is a federal republic in which the national (or “federal”) government shares sovereignty with state governments.

At both the federal and the state levels, there are three branches of the government: the legislative branch that makes laws; the executive branch that implements and enforces the laws; and the judicial branch that interprets the laws. At the federal level, the legislative branch, the U.S Congress, is composed of the Senate and the House of Representative.

The executive branch is headed by the President and includes various departments and agencies. The judicial branch includes the Supreme Court and trial and appellate courts. State governments have similar structures.

The U.S government is established by the Constitution. The three branches of government are independent of each other, but enjoy checks and balances over the others. For examples, Supreme Court justices are nominated by the President and are subject to approval by the Senate. Legislation adopted by Congress must be signed by the President to become law. The Supreme Court has the ultimate authority to interpret laws passed by Congress.

Generally speaking, matters that affect national interests, national security or have intra-state applications are within the jurisdiction of the federal government. Matters that affect only a state’s interests, the interests of its citizens or have application only within the state, such as land zoning, are within the state’s power to govern.