A diagram of the federal government shows three branches created by the U.S. Constitution — legislative, executive, and judicial — connected by the checks each branch holds over the others, and sitting alongside a separate axis of authority shared with the states. Article I creates Congress, Article II creates the presidency, and Article III creates the federal courts. The lines between them are not decorative. They are the mechanisms that keep any one branch from acting alone.
The Legislative Branch
Article I places all federal lawmaking power in Congress, which is split into two chambers.1Constitution Annotated. Article I – Legislative Branch The House of Representatives has 435 voting members, a figure fixed by the Permanent Apportionment Act of 1929 and distributed among the states by population.2History, Art and Archives, U.S. House of Representatives. The Permanent Apportionment Act of 1929 The Senate has 100 members, two from every state regardless of population. House members serve two-year terms. Senators serve six-year terms, with roughly one-third of the Senate up for election every two years.3U.S. Capitol Visitor Center. The U.S. Senate
Who Can Serve
A House member must be at least 25 years old, a U.S. citizen for at least seven years, and a resident of the state they represent. A senator must be at least 30, a citizen for nine years, and a resident of their state at the time of election.4Constitution Annotated. Overview of House Qualifications Clause
What Congress Does
Article I, Section 8 lists the core powers: collecting taxes, borrowing money, regulating commerce with foreign nations and among the states, setting rules for naturalization and bankruptcy, establishing post offices, and declaring war.5Cornell Law Institute. U.S. Constitution Article I Section 8 Congress also controls federal spending through annual appropriations. No money leaves the Treasury without legislative authorization, and that power over the purse reaches every program and agency in the executive branch.
The Executive Branch
Article II vests executive power in the President, who is responsible for enforcing the laws Congress passes.6Congress.gov. Overview of Article II, Executive Branch The President is Commander in Chief of the armed forces, negotiates treaties, and appoints federal officers — judges, ambassadors, Cabinet members — all subject to Senate confirmation.7Constitution Annotated. Article II Section 2 Clause 2
The Cabinet and Executive Departments
Fifteen executive departments do the daily work of the federal government, covering national defense, foreign policy, agriculture, transportation, veterans’ services, and more. Each department is led by a secretary who advises the President and manages a large civil-service workforce. The Department of Justice is the exception, headed by the Attorney General. Beyond the departments, dozens of independent agencies and regulatory commissions handle specialized areas like environmental protection, securities regulation, and aviation safety.
How the President Is Elected
The President is not chosen by direct popular vote. Voters in each state choose electors who form the Electoral College, made up of 538 electors total. A candidate needs at least 270 electoral votes to win. Most states award all their electoral votes to whichever candidate wins the state’s popular vote. Maine and Nebraska split theirs using a proportional method.8National Archives. What Is the Electoral College? If the President can no longer serve, the Vice President is first in line, followed by a longer chain set out in the Presidential Succession Act of 1947.9USAGov. Order of Presidential Succession
The Judicial Branch
Article III establishes a federal court system headed by the Supreme Court and authorizes Congress to create lower courts.10Congress.gov. U.S. Constitution – Article III The system today includes 94 district courts, where most federal cases begin, and 12 regional appeals courts. A 13th appellate court, the U.S. Court of Appeals for the Federal Circuit, handles specialized matters like patent disputes and international trade.11United States Courts. About the U.S. Courts of Appeals Additional specialized courts handle federal tax disputes and claims against the government.
Federal courts hear cases involving the Constitution, federal statutes, treaties, maritime disputes, and controversies between parties from different states.10Congress.gov. U.S. Constitution – Article III Lower-court decisions can be appealed upward, with the Supreme Court as the final word.
Judicial Tenure
Article III judges — Supreme Court justices, appeals court judges, and district court judges — hold their positions during “good behavior.” In practice that means a lifetime appointment with no mandatory retirement age. They can be removed only through impeachment by the House and conviction by the Senate.12United States Courts. Types of Federal Judges The insulation from political pressure is intentional. Not every federal judge has lifetime tenure, however. Magistrate judges, who handle preliminary matters in district courts, serve renewable eight-year terms.
Checks and Balances
The lines connecting the branches represent the tools each one uses to limit the others. These operate every day, not just in crises.
Executive Checks on Congress
The President can veto any bill Congress passes. A vetoed bill dies unless both chambers vote to override by a two-thirds majority, a threshold rarely met.13Constitution Annotated. Article I Section 7 Even the threat of a veto often pushes lawmakers to change a bill before it reaches the President’s desk.14National Archives and Records Administration. The Presidential Veto and Congressional Veto Override Process
Congressional Checks on the Executive
The Senate must confirm the President’s nominees for Cabinet positions, federal judgeships, and other high-ranking offices.7Constitution Annotated. Article II Section 2 Clause 2 Congress controls appropriations, and the executive branch cannot spend money without them. In extreme cases the House can impeach federal officers, including the President, with the Senate conducting the trial.15Constitution Annotated. Article I Section 2
Judicial Review
Federal courts can strike down laws passed by Congress or actions taken by the President that violate the Constitution. This power, called judicial review, is not spelled out in the constitutional text. The Supreme Court established it in the 1803 case Marbury v. Madison, reasoning that because the Constitution is the supreme law, any ordinary statute that conflicts with it cannot stand.16Constitution Annotated. ArtIII.S1.3 Marbury v. Madison and Judicial Review It remains one of the most consequential features of the American system: a single court decision can reshape entire areas of law.
Federal Power and State Power
The diagram extends beyond the three branches in Washington. The Constitution creates a dual system in which the federal government and state governments each hold distinct areas of authority.
The Supremacy Clause in Article VI establishes that the Constitution and federal laws made under it are the “supreme Law of the Land,” so federal law overrides conflicting state law.17Constitution Annotated. Article VI Clause 2 – Supremacy Clause Federal power is not unlimited, though. The Tenth Amendment reserves all powers not granted to the federal government, and not prohibited to the states, to the states or the people.18GovInfo. 10th Amendment US Constitution – Reserved Powers
States handle most of the governing that touches daily life: running elections, issuing marriage licenses, operating public schools and hospitals, licensing professionals, and managing their own court systems and police forces. The federal government focuses on areas the Constitution assigns to it, such as national defense, immigration, interstate commerce, and foreign relations. Where those areas overlap — health care regulation, environmental law, criminal justice — you find some of the most contested territory in American law.
How the Constitution Gets Amended
Article V allows the structure itself to change, but the bar is deliberately high. An amendment can be proposed by a two-thirds vote in both chambers of Congress or by a constitutional convention called at the request of two-thirds of state legislatures. Ratification then requires approval by three-fourths of the states, either through their legislatures or through special conventions, depending on which route Congress specifies.19Constitution Annotated. Overview of Article V, Amending the Constitution All 27 amendments so far have come through the congressional proposal route. No constitutional convention has been called since the original one in 1787.
How Agencies Fit In
Congress writes laws in broad strokes. The detailed rules that actually govern most industries and activities come from federal agencies through notice-and-comment rulemaking under the Administrative Procedure Act. An agency publishes a proposed rule in the Federal Register, opens a public comment period (typically 30 to 60 days), reviews and responds to comments, and then publishes a final rule that generally cannot take effect until at least 30 days after publication.20Office of the Law Revision Counsel. 5 USC 553 – Rule Making Regulations in force are compiled in the Code of Federal Regulations.21Federal Register. Federal Register Office
Agencies sit within the executive branch but exercise a kind of quasi-legislative power when they write rules. Those rules carry the force of law, and they can be challenged in court. That is how all three branches end up involved in a single regulation Congress never explicitly voted on.