How Congress Works - A Plain-English Guide

Updated: October 30, 2026

Congress is the legislative branch of the U.S. government, the part that writes federal laws. It has two parts: the Senate, with 100 senators (two per state) serving six-year terms, and the House of Representatives, with 435 voting members serving two-year terms. A bill must pass both before the president can sign it into law.

Two chambers - the Great Compromise

At the Constitutional Convention in 1787, large and small states disagreed about representation. Large states wanted seats based on population; small states wanted every state to count equally. The solution, known as the Great Compromise (or Connecticut Compromise), created two chambers:

The House, where seats depend on population
The Senate, where every state has exactly two senators

That is why the 2025 civics test accepts "equal representation (for small states)" and "the Great Compromise" as answers to "Why does each state have two senators?"

The Senate

Size: 100 senators, 2 from each of the 50 states
Term: 6 years, with about one-third of seats up for election every two years
Who they represent: all the people of their state
Who elects them: citizens from their state (direct election of senators comes from the 17th Amendment, ratified in 1913)
Requirements: at least 30 years old, a U.S. citizen for at least 9 years, and a resident of the state
Special powers: confirms many presidential appointments (including federal judges and Cabinet members), approves treaties, and holds the trial if an official is impeached

The Vice President is the President of the Senate and can cast a tie-breaking vote.

The House of Representatives

Size: 435 voting members
Term: 2 years, with every seat up for election at once
Who they represent: the people in their congressional district
Who elects them: citizens from their district
Requirements: at least 25 years old, a U.S. citizen for at least 7 years, and a resident of the state
Special powers: starts all bills to raise revenue (taxes) and can impeach federal officials
Leader: the Speaker of the House, chosen by the members (Mike Johnson, as of the USCIS test updates page in 2026)

The number of representatives per state is based on population and is recalculated after each 10-year census. That is why some states have many more representatives than others: they have more people. Washington, D.C., and the U.S. territories send nonvoting delegates or a resident commissioner.

Why such short House terms?

Two-year terms force representatives to face voters often. The 2025 test answer to "Why do U.S. representatives serve shorter terms than U.S. senators?" is to more closely follow public opinion. Senators' longer terms were designed to give the Senate more stability.

How a bill becomes a law

Introduction: a member of the House or Senate introduces a bill. Anyone can suggest an idea, but only members of Congress can introduce one.
Committee: the bill goes to a committee that studies it, holds hearings, and may change it. Most bills never leave committee.
Floor vote: if the committee approves it, the full chamber debates and votes.
The other chamber: the bill goes to the other chamber, which follows its own process.
Agreement: both chambers must pass the exact same text. Differences are worked out, often by a conference committee or by passing amended versions back and forth.
The president: the president can sign the bill into law or veto it.
Override: Congress can override a veto with a two-thirds vote in both the House and the Senate.

This process is a good example of checks and balances among the three branches.

What else Congress does

Under Article I of the Constitution, Congress's powers include:

Writing laws
Declaring war
Making the federal budget and setting taxes
Printing and coining money
Regulating trade between states and with other countries
Creating lower federal courts
Overseeing the executive branch through hearings and investigations

On the 2025 test, "Name one power of the U.S. Congress" is an asterisk question, and the accepted answers are writes laws, declares war, and makes the federal budget.

Congress questions on the 2025 civics test

The official list includes many Congress questions:

What are the two parts of the U.S. Congress? Senate and House (of Representatives)
How many U.S. senators are there? One hundred (100)
How long is a term for a U.S. senator? Six (6) years
How many voting members are in the House? Four hundred thirty-five (435)
How long is a term for a member of the House? Two (2) years
How many senators does each state have? Two (2)
Some states have more representatives than others. Why? Because of the state's population
Who is one of your state's U.S. senators now? Answers vary
Name your U.S. representative. Answers vary
What is the name of the Speaker of the House now? Check uscis.gov/citizenship/testupdates

The "answers vary" questions depend on where you live. See find your senators and representative and civics questions with changing answers. If you live in D.C. or a territory, USCIS has special accepted answers, such as saying that D.C. has no U.S. senators.

In Civio's Exam Mode, three of the 20 questions are about your own state, so you get used to answering these personal questions under test conditions.

Frequently asked questions

How many members does Congress have?

535 voting members: 100 senators and 435 representatives. There are also nonvoting delegates from Washington, D.C., and the U.S. territories.

Why do senators serve six years and representatives two?

Short House terms keep representatives close to public opinion, while longer Senate terms give that chamber more stability. The civics test answer for the House is "to more closely follow public opinion."

Who is the leader of the House of Representatives?

The Speaker of the House, elected by the House members. As of the USCIS test updates page in 2026 it is Mike Johnson, but check the page before your interview.

Can Congress pass a law without the president?

Yes, by overriding a presidential veto with a two-thirds vote in both the House and the Senate.

How many representatives does my state have?

It depends on your state's population, based on the most recent census. The House website and your state election office list your state's districts and members.

Prepare for the civics test with Civio: every official question from the 2025 USCIS civics test, Exam Mode with your state's questions, and spaced repetition.

Informational article, not legal advice. Civio is not affiliated with USCIS or any government agency; always check current requirements at uscis.gov.