The United States government is a constitutional system that splits authority three ways at the federal level — Congress writes the laws, the President carries them out, and the courts interpret them — and then splits authority again between Washington and the fifty states. If you want to understand how the US government works, start there: no single office runs the country, and most of the rules that touch your daily life are made closer to home than you might think.
The framework comes from the Constitution, ratified in 1788. Its first three articles create the three federal branches. The Tenth Amendment reserves everything else to the states or the people. Every other feature of American government — agencies, budgets, elections, courts — grows out of that basic division.
The Three Federal Branches
Congress Makes the Laws
Article I places all federal lawmaking power in Congress, which has two chambers: the House of Representatives and the Senate. House seats are apportioned by state population; each state gets two senators regardless of size, for one hundred senators total.1Congress.gov. Constitution of the United States – Article I
Congress does more than write statutes. It controls the federal budget, confirms presidential appointments, and holds the sole authority to declare war. A bill has to pass both chambers in identical form before it can go to the President for a signature.
The President Carries Them Out
Article II vests executive power in the President, who serves a four-year term and is commander-in-chief of the armed forces.2Cornell Law Institute. U.S. Constitution – Article II The job is to execute the laws Congress passes, negotiate treaties, and set the direction of federal agencies. Fifteen executive departments — headed by Cabinet secretaries the President nominates — handle everything from diplomacy at the State Department to tax collection at Treasury.3The White House. The Executive Branch
Presidents also issue executive orders, which direct how federal agencies operate. Those orders have to rest on the Constitution or on a statute Congress already passed. A president cannot spend money Congress hasn’t appropriated or create or abolish a federal department by executive order. Courts can strike down orders that exceed presidential authority, and a later president can revoke them.
The Courts Interpret Them
Article III creates the Supreme Court and lets Congress establish lower federal courts.4Congress.gov. U.S. Constitution – Article III Federal judges hold their seats during “good behaviour,” which in practice means for life. That insulation is the point: judges who don’t have to face voters or reappointment can rule against powerful officials without losing their jobs. By statute, the Supreme Court has one Chief Justice and eight associate justices.5Office of the Law Revision Counsel. 28 USC 1 – Number of Justices; Quorum
Below the Supreme Court sit thirteen courts of appeals and ninety-four district courts covering every state, Washington, D.C., and four U.S. territories.6United States Courts. About U.S. District Courts Most federal cases start in a district court, get one appeal at the circuit level, and go no further. The Supreme Court only hears cases it agrees to take.
How the Branches Keep Each Other in Check
Separation of powers only works because each branch has tools to push back on the others.
The President’s main check on Congress is the veto. A vetoed bill cannot become law unless two-thirds of members voting in each chamber, with a quorum present, override the veto.7National Archives and Records Administration. The Presidential Veto and Congressional Veto Override Process That threshold is high enough that Congress has historically overridden only about seven percent of vetoes, so the threat alone often reshapes a bill before it lands on the President’s desk.
The courts check both other branches through judicial review, established by the Supreme Court in the 1803 case Marbury v. Madison.8Constitution Annotated. Marbury v. Madison and Judicial Review Federal courts can declare a statute or an executive action unconstitutional and void it. The power isn’t spelled out in the Constitution. It grew from Chief Justice John Marshall’s reasoning that someone has to decide when a law contradicts the foundational document, and courts are the natural choice.9National Archives. Marbury v. Madison (1803)
Congress has its own set of levers. The Senate confirms the President’s nominees for federal judgeships and Cabinet positions before they take office.10Constitution Annotated. Overview of Appointments Clause Congress controls the purse: no money leaves the Treasury without an appropriation. And the House can impeach federal officials, including the President, while the Senate holds the trial and can remove the official with a two-thirds vote.11Constitution Annotated. Overview of Impeachment Clause
Federal, State, and Local: Who Does What
Power in the United States isn’t stacked in a single pyramid. It’s divided between Washington and the states under a system called federalism. The Tenth Amendment makes the split explicit: any power the Constitution doesn’t hand to the federal government, and doesn’t forbid the states from using, belongs to the states or the people.12Congress.gov. U.S. Constitution – Tenth Amendment
Each state has its own constitution, governor, legislature, and court system. States handle most criminal law, property rules, family law, professional licensing, and public education. When you get a driver’s license, send a child to public school, or face a charge for theft or assault, you’re dealing with state law and state institutions, not federal ones.
Below the state sit counties, cities, towns, and special districts. These local governments exist only because their state authorized them; they have no independent constitutional standing. Mayors and county commissioners run zoning, trash collection, local police, fire departments, and property taxes. In a single week, one resident might interact with all three levels without noticing which is which.
When Federal and State Law Collide
The Supremacy Clause in Article VI settles conflicts: the Constitution, federal statutes, and treaties are “the supreme Law of the Land,” and state judges are bound by them regardless of what their own state’s law says.13Constitution Annotated. Article VI – Clause 2, Supremacy Clause When a valid federal law directly conflicts with a state law, the federal law wins.
Courts work through these clashes using a doctrine called federal preemption. Sometimes Congress writes explicit language into a statute saying it overrides state law on the topic. Other times, federal regulation is so thorough that courts infer Congress meant to occupy the entire field. The Supreme Court generally presumes federal law does not displace state law unless Congress made its intent clear, so preemption is not automatic just because both levels regulate the same subject.
Where the Money Comes From and Where It Goes
Federal revenue comes mostly from individual income taxes and payroll taxes. The Social Security payroll tax is 6.2 percent of an employee’s wages, matched by the employer, on earnings up to $184,500 in 2026.14Social Security Administration. Contribution and Benefit Base Medicare adds another 1.45 percent with no wage cap. Individual income tax returns are due April 15 each year, with an October 15 deadline for taxpayers who request an extension.15Internal Revenue Service. Need More Time to File? Don’t Wait, Request an Extension
On the spending side, the federal budget divides into two categories. Mandatory spending — programs like Social Security and Medicare whose funding is set by existing law — accounts for roughly two-thirds of federal outlays and doesn’t need an annual vote.16U.S. Treasury Fiscal Data. Federal Spending Discretionary spending covers what Congress appropriates each year: military equipment, highway maintenance, research, education, and much more.
The federal government routinely spends more than it collects and borrows the difference. A statutory debt ceiling caps how much the Treasury can borrow, and Congress has to vote to raise or suspend that limit before the Treasury runs out of room. When lawmakers delay, the Treasury turns to accounting maneuvers to keep paying obligations. If those run out without action, the government faces default.
What the Government Actually Does
National defense is the biggest single discretionary commitment. The military — Army, Navy, Air Force, Marines, Space Force, and Coast Guard — dominates the discretionary budget every year. The federal government also funds and maintains the interstate highway system, bridges, and public transit, often by sending grants and fuel-tax revenue to state and local transportation agencies.
Social safety-net programs cover tens of millions of Americans. Social Security pays monthly benefits to retired and disabled workers, funded by the payroll taxes described above.17Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates Medicare covers healthcare for people sixty-five and older. Medicaid, jointly funded by the federal government and the states, serves lower-income residents. All three run on autopilot under existing law, which is why they sit in the mandatory column.
Law enforcement spans all three levels. Federal agencies like the FBI and DEA handle crimes that cross state lines, involve federal property, or fall under federal statutes. Federal drug trafficking can carry mandatory minimum sentences of five to ten years depending on the substance and quantity.18Department of Justice. Frequently Used Federal Drug Statutes State and local police handle almost everything else, from traffic stops to assault investigations.
Public education is overwhelmingly a state and local job. States set curriculum standards, certify teachers, and fund schools mostly through property and sales taxes. The federal Department of Education plays a supporting role, providing money and oversight for special education, disability accommodations, and student privacy. Decisions about what happens in a classroom are made at the state and district level, not in Washington.
The Rules Behind the Laws
Congress often writes statutes in broad terms and hands the details to federal agencies. The Environmental Protection Agency doesn’t just enforce the Clean Air Act; it writes the specific pollution limits industries must follow. Those agency-written rules carry legal force much like statutes, which means a huge share of the rules Americans live under come from unelected officials inside executive agencies.
The process has guardrails. Before a new rule takes effect, the agency has to publish a proposed version in the Federal Register, the government’s official daily publication for agency rules and public notices.19Federal Register. Federal Register 101 The public gets a comment period, and the agency has to respond to significant concerns before finalizing the rule. Final rules generally cannot take effect until at least thirty days after publication. Courts can invalidate rules that exceed an agency’s authority or skip required procedures, and Congress can pass legislation overriding a regulation it disagrees with.
What Citizens Owe the System
Government doesn’t run in one direction. Citizens have legal obligations that keep the machinery working.
- Federal income tax returns are due April 15 each year. Filing late or paying late triggers penalties and interest. An extension gives you more time to submit paperwork, not more time to pay.15Internal Revenue Service. Need More Time to File? Don’t Wait, Request an Extension
- Federal law declares that all citizens have an obligation to serve as jurors when summoned, and state courts impose similar requirements. Ignoring a jury summons can bring fines or contempt-of-court charges.20Office of the Law Revision Counsel. 28 USC 1861 – Declaration of Policy
- Male U.S. citizens and immigrant non-citizens between eighteen and twenty-five have historically been required to register with the Selective Service System within thirty days of turning eighteen. Beginning in December 2026, the FY2026 National Defense Authorization Act replaces self-registration with automatic registration drawn from existing federal databases.
- Voting in federal elections is a right in the United States, not a legal obligation, but casting a ballot requires registration. Each state sets its own registration rules and deadlines, which can fall as early as thirty days before Election Day. Many states also require voters to register with a political party to vote in primaries.21Vote.gov. Register to Vote
Taxes fund the budget. Jurors staff the courts. Voters pick the officials who run the other two branches. The system described above only holds together when the people it governs hold up their end.