The two chambers grew out of the Connecticut Compromise of 1787, which gave large states representation by population in the House and small states equal votes in the Senate. The framers also intended the chambers to differ in temperament. The House, close to the people with short terms, would reflect public opinion, while the Senate, with longer terms and originally chosen by state legislatures, would be more deliberate. Senators have been elected directly since the Seventeenth Amendment in 1913.
This guide compares the chambers side by side, from who serves and how they are led to how they make decisions and what each can do alone.
Bicameralism slows lawmaking by requiring two differently constituted bodies to agree. In Federalist No. 62 and No. 63, James Madison argued that the Senate would provide stability and guard against rash legislation driven by passing passions. Critics have long noted that equal state representation gives voters in small states more weight, a design that can only be changed with a state's own consent under Article V.
Every bill and joint resolution must pass both chambers in identical form. Chambers resolve differences by passing each other's bills, exchanging amendments, or appointing a conference committee, a once routine practice now rarely used. Budget resolutions set shared spending targets, and concurrent resolutions handle matters such as adjournment. When different parties control the two chambers, disagreements between them become a major source of gridlock.
In the House, the Rules Committee writes a special rule for each major bill, limiting debate and amendments, and a determined majority can pass bills quickly. The Senate allows unlimited debate and generally unrestricted amendments, so most business moves by unanimous consent, any senator can place a hold, and ending a filibuster requires 60 votes. House members can bypass leaders with a discharge petition, while senators can slow almost anything individually.
The House chooses its Speaker, who presides, controls the agenda, and stands second in line to the presidency. The Constitution makes the Vice President the President of the Senate, voting only to break ties, and provides for a President pro tempore. Real power in the Senate rests with the majority leader, who by precedent is recognized first and controls the floor schedule.
Representatives must be 25, citizens for seven years, and residents of their state, and serve two-year terms. Senators must be 30, citizens for nine years, and state residents, and serve six-year terms, with a third of the Senate up every two years. House size has been fixed at 435 since 1913, and after the 2020 census the average district held about 761,000 people. District lines are redrawn after each census, while Senate seats always cover entire states.
The Constitution requires bills raising revenue to originate in the House, a role carried out by the Ways and Means Committee, and gives the House the sole power to impeach. The Senate alone confirms nominees, including judges, through advice and consent, approves treaties by two thirds, and tries impeachments. If no presidential candidate wins an Electoral College majority, the House chooses the President and the Senate chooses the Vice President.
See the full institution in how Congress works, explore the Senate's defining rule in the filibuster explained, or follow a bill through both chambers in how a bill becomes law.