The United States is a federal presidential constitutional republic, in which the President serves as both head of state and head of government, an elected bicameral Congress makes the laws, and an independent Supreme Court interprets them. This system, established by the Constitution ratified in 1788, divides power among three co-equal branches and between the national government and 50 states, with the goal that no single person or institution can dominate the others.
How the Three Branches Work
American government rests on the separation of powers into three branches that share authority through a system of checks and balances. The executive branch, led by the President, enforces federal law, commands the armed forces, conducts foreign policy, and appoints senior officials and judges. The legislative branch, the Congress, writes and passes laws, controls federal spending, and can override a presidential veto with a two-thirds vote in both chambers. The judicial branch, headed by the Supreme Court, reviews laws and executive actions and can strike down those it finds unconstitutional.
Each branch can limit the others. The President can veto legislation, but Congress can override it and must confirm many appointments. Congress can impeach and remove a president or judge, while the courts can invalidate acts of both other branches. This mutual restraint is the defining feature of the U.S. constitutional design.
The Presidency and the Executive Branch
Unlike parliamentary systems, the United States combines the ceremonial role of head of state and the working role of head of government in one office. The President is elected to a four-year term through the Electoral College rather than by direct national popular vote, and the Twenty-second Amendment limits anyone to two elected terms. The Vice President succeeds the President if the office becomes vacant and also presides over the Senate, casting a vote only to break a tie.
Below the President sits the Cabinet, whose members lead departments such as State, Treasury, Defense, and Justice. These officials are nominated by the President and must be confirmed by the Senate. A vast federal bureaucracy of agencies carries out the day-to-day work of governing, from collecting taxes to managing national parks.
Congress: The Legislature
Legislative power is vested in a bicameral Congress made up of two chambers. The Senate has 100 members, two from each state regardless of population, serving staggered six-year terms. The House of Representatives has 435 voting members apportioned among the states by population, each serving a two-year term. This structure balances the interests of small and large states.
A bill must pass both chambers in identical form and be signed by the President before it becomes law. Congress also holds the "power of the purse," meaning no federal money can be spent without its approval, and the Senate ratifies treaties and confirms federal appointments. These powers make the legislature a central check on the executive.
Federalism and the States
The United States is a federation, so authority is shared between the national government in Washington, D.C., and the 50 individual states. Each state has its own constitution, governor, legislature, and court system, and exercises powers not specifically granted to the federal government. States run elections, operate public schools, manage local policing, and set much of their own civil and criminal law.
The Tenth Amendment reserves undelegated powers to the states or the people, while the Supremacy Clause ensures that valid federal law prevails when conflicts arise. This layered arrangement allows considerable variation in policy from one state to another. For more context on the country itself, see our united states country guide.
Constitution, Rights, and History
Born from the Revolution against British rule, the United States declared independence in 1776 and adopted its Constitution in 1788, creating one of the first modern democratic republics. The Bill of Rights, the first ten amendments ratified in 1791, guarantees freedoms such as speech, press, religion, and assembly, along with protections for the accused. The Constitution has been amended 27 times in total.
Major turning points reshaped the system over time. The Civil War (1861–1865) preserved the Union and ended slavery, and later amendments extended citizenship and voting rights. Women gained the right to vote nationally in 1920, and the civil rights movement of the 1960s dismantled legal segregation and expanded voting protections. Today a two-party landscape dominated by the Democratic and Republican parties shapes most elections.
Frequently Asked Questions
What type of government does the United States have?
It is a federal presidential constitutional republic. Power is split among three branches and shared between a national government and 50 states, all operating under a written constitution.
Who is the head of state of the United States?
The President is both head of state and head of government, elected to a four-year term through the Electoral College and limited to two terms.
What are the two houses of Congress?
Congress is bicameral, made up of the Senate, with 100 members serving six-year terms, and the House of Representatives, with 435 voting members serving two-year terms.
What is the highest court in the United States?
The Supreme Court is the highest court. Its nine justices are appointed by the President, confirmed by the Senate, and serve for life, with the power to declare laws unconstitutional.