The most useful facts about the US government are structural: it runs under the oldest written national constitution still in force, a document of roughly 4,500 words that has been amended only 27 times; it splits authority across three branches that actively block one another; and it employs more than two million civilians to carry out laws that only Congress can fund. Everything else, from how presidents are chosen to why Washington D.C. residents have no senators, follows from those basics.
The Constitution Is Short, Old, and Hard to Change
The original Constitution runs about 4,500 words including signatures, one of the shortest founding documents of any modern nation. It took effect after conventions in nine of the original thirteen states ratified it, as required by Article VII.1Congress.gov. U.S. Constitution – Article VII No other written national constitution has been in continuous operation longer. The brevity was deliberate. The framers laid down a framework and left the details to legislation, court interpretation, and an amendment process built to be difficult.
How difficult? An amendment can be proposed either by a two-thirds vote of both the House and Senate or by a convention called by two-thirds of state legislatures. It only takes effect when three-fourths of the states ratify it.2Congress.gov. Overview of Article V, Amending the Constitution In more than two centuries, that bar has been cleared 27 times.
The first ten amendments, the Bill of Rights, were ratified together on December 15, 1791, and set out limits on what the federal government can do to individuals, including protections for speech, religious exercise, and peaceful assembly.3National Archives. The Bill of Rights: A Transcription The other seventeen have arrived at irregular intervals since, covering everything from ending slavery to giving women the vote to capping the presidency at two terms. Every amendment has been ratified by state legislatures except one: the Twenty-First, which repealed Prohibition, went through state conventions.
Three Branches, and Each One Can Block the Others
Federal authority is divided among the Legislative branch (Congress), the Executive branch (the president and federal agencies), and the Judicial branch (the federal courts). None of them can operate freely without the others pushing back, and that friction is the point.
Congress writes and passes laws. The president can veto any bill. Congress can override a veto, but only with a two-thirds vote in both chambers, a margin that rarely materializes on contested legislation.4Congress.gov. U.S. Constitution Article I Section 9 Clause 7 The president nominates federal judges, including Supreme Court justices, but the Senate must confirm each one.5United States Senate Committee on the Judiciary. Supreme Court Nominations The courts, in turn, can strike down laws or executive orders that violate the Constitution, a power called judicial review that the Supreme Court claimed for itself in the 1803 case Marbury v. Madison.6Justia. Marbury v. Madison, 5 U.S. 137 (1803) Congress controls the courts’ funding and holds the power to impeach and remove federal judges and even the president.
How the President Is Chosen and Limited
The president is not elected by a nationwide popular vote. Under Article II, each state appoints electors equal to its combined number of senators and House members. The Electoral College totals 538 votes, and a candidate needs 270 to win.7National Archives. Distribution of Electoral Votes The Twenty-Third Amendment gives Washington D.C. three electors, matching the least populous state.8Congress.gov. U.S. Constitution – Twenty-Third Amendment
Because every state starts with two electoral votes from its Senate seats regardless of population, smaller states carry slightly more weight per voter. A candidate can win the presidency while losing the national popular vote, which has happened five times.
Whoever wins is capped by the Twenty-Second Amendment, ratified in 1951, at two elected terms.9Congress.gov. U.S. Constitution – Twenty-Second Amendment If someone inherits the office more than halfway through another president’s term, that partial term doesn’t count against the limit. With more than two years remaining, it does. If a president leaves office early, the Presidential Succession Act names the vice president first in line, then the Speaker of the House, then the president pro tempore of the Senate, then cabinet secretaries in the order their departments were created.10USAGov. Order of Presidential Succession
Congress Controls Every Dollar
Article I, Section 8 gives Congress the power to levy taxes and spend public money.11Congress.gov. U.S. Constitution Article I Section 8 Clause 1 Article I, Section 9 makes that control absolute: “No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law.”4Congress.gov. U.S. Constitution Article I Section 9 Clause 7 No federal agency can spend a cent unless Congress specifically approves it.
This “power of the purse” is one of the strongest checks the legislature holds over the other branches. The president proposes a budget; Congress decides what actually gets funded. When lawmakers and the White House cannot agree on spending bills, many federal operations pause in a government shutdown until new funding is enacted.
Two Chambers, Two Different Logics
Congress has two chambers, and they represent the country in opposite ways. The Senate assigns two seats to each state, whether that state has half a million residents or forty million.12Congress.gov. U.S. Constitution Article I Section 3 The House distributes its seats by population, recalculated after each ten-year census.13Congress.gov. U.S. Constitution Article I Section 2 The total number of House seats has been fixed at 435 since the Permanent Apportionment Act of 1929.14History, Art & Archives, U.S. House of Representatives. The Permanent Apportionment Act of 1929
Both chambers must pass identical bill language before it can go to the president for signature. Every piece of federal legislation, in other words, has to satisfy both a body where Wyoming equals California and a body where it does not.
The Federal Workforce Is Massive
As of January 2026, the federal government employed more than 2,035,000 civilians across hundreds of agencies, making it the country’s largest single employer.15Office of Personnel Management. Workforce Size and Composition That figure does not include roughly 1.3 million active-duty military personnel. Fifteen executive departments, each led by a cabinet secretary appointed by the president, handle most of the day-to-day work of enforcing federal laws and running programs.16The White House. The Executive Branch Dozens of independent agencies, from the Environmental Protection Agency to the Social Security Administration, handle specialized functions outside those departments. The work ranges from air traffic control to veterans’ healthcare to national park maintenance.
Federalism Reserves Most Powers to the States
The federal government holds only the powers the Constitution specifically grants it. Everything else belongs to the states or to the people. The Tenth Amendment says so directly: “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”17Congress.gov. U.S. Constitution – Tenth Amendment
In practice, states set their own criminal codes, run their school systems, regulate most professional licenses, manage elections, and control land use. The federal government handles defense, immigration, interstate commerce, and the other powers listed in Article I, Section 8. When state and federal laws conflict, Article VI’s Supremacy Clause provides that federal law wins.18Congress.gov. U.S. Constitution – Article VI The line between the two is rarely clean, and disputes over where it falls have produced some of the most consequential Supreme Court cases in American history.
Washington D.C. sits outside the state system entirely. It is a federal district under the direct authority of Congress, a design meant to keep the seat of government independent from any single state. For the nearly 700,000 people who live there, the consequence is real: they pay federal income taxes, serve in the military, and follow federal laws, but they have no voting senators and only a non-voting delegate in the House. The Twenty-Third Amendment gave them three electoral votes for presidential elections in 1961, but Congress still retains the ability to review and override laws passed by D.C.’s local government, a level of federal control no state faces.