The executive branch enforces laws. The judicial branch interprets laws. But it is in the law-making legislative branch, says Howard Schweber, a political science professor at the University of Wisconsin, “that the people deliberate and arrive at an agreement about the common good.”

When writing the U.S. Constitution, the framers built in three branches of federal government to ensure a separation of powers, and, as Article I states, “All legislative powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.”

“The point of the Constitution was to replace a system in which the national government could only make laws that affected states in their relations with one another,” Schweber says. “The new system would be one in which the national government would make laws that applied to everyone—true national legislation.”

The framers referred to Congress as the “first branch,” establishing its structure and authority in Article I.

“Congress has the power to levy taxes, raise and maintain an army and navy, regulate interstate commerce, and pass any law it deems ‘necessary and proper,’ among a host of other powers like confirming judges and executive branch officials,” says Joshua Huder, senior fellow at the Government Affairs Institute at Georgetown University.

Beyond these powers, here are 11 things you may not know about the legislative branch.

The Senate was designed to represent the states, while the House was intended to represent the nation.

The House, according to Schweber, was the expression of democracy, while the Senate was the expression of federalism. “The Senate was the place where each state's interest could be asserted; the House was expected to be populated by virtuous, public-minded individuals who would only care for the national welfare,” he says. “So the House was intended to represent the people—that's why there are a large number of representatives each attached to a particular number of people. The Senate, by contrast, is driven by the desire to ensure that each state would stand in a relationship of equality with the others.”

The framers looked to the British. 

“The American system is modeled quite shamelessly on Britain’s, where a House of Commons and House of Lords each held legislative power,” says Jeffrey Engel, director of the Center for Presidential History at Southern Methodist University. “In essence, the House of Representatives/House of Commons represents the common people’s interests, and the Lords/Senate, the elites. 

This is why senators enjoy six-year terms, and were originally selected not by popular vote but rather by each state’s legislature: Because they, like lords, were supposed to be further removed from the popular politics of the rabble and thus better insulated to consider great matters of state.”

Alexander Hamilton argued that senators should have lifelong terms.

Alexander Hamilton
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Alexander Hamilton (1755–1804).

The framers of the Constitution were at odds when it came to determining the length of Senate terms. According to the United States Senate Historical Office, six years was a compromise.

“Framers who favored longer terms argued that it would help the Senate check the democratic impulses of the House,” writes the office’s Betty K. Koed. “James Madison suggested a term of seven or nine years to hamper such influences. Alexander Hamilton argued that only lifetime terms could keep the ‘amazing violence and turbulence of the democratic spirit’ in check. Others wanted shorter terms to keep the Senate accountable.”

And, until the 17th Amendment was ratified in 1913, senators were selected by state legislatures rather than elected by voters.

The House has the power to name the president in case of a tie.

The Electoral College, noted in Article II, dictates the selection of the president occurs on a state-by-state basis rather than by popular vote. “So a tie in the Electoral College meant that the states had already spoken and failed to reach a decision,” Schweber says. “Turning the matter over to the Senate at that point would have been to reiterate the same failure of decision-making.”

And the House, Engel says, is where real sovereignty lies.

“Remember, the Constitution begins “We the people,” and the House most closely represents the broadest representation of the nation as a whole,” he says. “If there is a dispute over whom should lead us all, it only makes sense for the group that really represents all facets of the nation to have the final say.”

The House has been called on to exercise this power twice: In 1800, after a tie between Thomas Jefferson and Aaron Burr, and in 1824, when John Quincy Adams was named president by the House, although Andrew Jackson won the popular vote.

The House has the power to impeach the president; the Senate then convicts or acquits.

Impeachment Trial, US Senate
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A ticket of admission to the Impeachment Trial of President Andrew Johnson in the United States Senate in 1868. The Senate fell one vote short of the necessary two-thirds majority to convict President Johnson.

The impeachment process mirrors the criminal prosecution model, in which a grand jury would first decide whether the evidence warranted bringing charges, then a petit jury would decide guilt or innocence. “The House would act as a grand jury, the Senate would then stand as a petit jury,” he says.

And, Engel adds, senators, “being more immune to the passions of popular politics,” were considered better able to weigh great matters of state. “They didn’t have to run for election every time they made a decision,” he says. “Hence, they appeared better ‘judges’ for an impeachment trial.”

The Senate was kept small—two members per state—for a reason.

“Since the point of the Senate was to express the positions of each state government, there was no need for a larger body,” Schweber says. “The important thing was the number of voting members for each state be equal.”

It was also expected, he adds, that senators would engage less in deliberation and more in the conveying of instructions from their state governments.

“By contrast, the members of the House were to represent the people in all their variations—a tacit admission that the states were conceived of as entities separate from their people,” he says.

Congressmen and women are not required to vote on all proposed legislation.

Voting buttons in the U.S. House of Representatives chamber
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Voting buttons in the U.S. House of Representatives chamber.

In fact, they don’t even have to vote if they are present, Engel says. “This is why, even though we all know there are 435 members of the House and 100 senators, we rarely see the numbers add up to that when votes are finally tallied.”

Between the House and the Senate, about 15,000 bills are introduced in any given Congress, Huder adds. “Only a few hundred receive votes on the House or Senate floors,” he says.

Filibusters aren’t just the stuff of movies.

Longest Filibuster in U.S. History
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Senator Strom Thurmond holds the record for longest filibuster while speaking against the Civil Rights Bill. 

The purpose of a filibuster, according to Huber, is to delay legislation from receiving a vote, and 60 votes—out of 100 senators—are required to cut one off. “This enables a minority faction of the Senate to block most legislation from passing the Senate,” he says.

Stewart’s Jefferson Smith spent 24 hours filibustering in 1939’s Mr. Smith Goes to Washington, but Strom Thurmond holds the official record, holding the floor for 24 hours and 18 minutes in 1957, in an attempt to block civil rights legislation.

Congress has authority to control the training and equipping of militias.

It can also call them up to enforce federal law, put down insurrections and repel invasions (Article I, Sec. 8), according to Schweber. “This observation just emphasizes the extent to which the new national government was expected to assume a significant portion of the roles previously played by states, a point that is sometimes overlooked by modern ‘states' rights’ advocates,” he says.

Congress has the power to regulate its own size.

Senate Chamber, 1867
Hulton-Deutsch Collection/Corbis/Getty Images
The Senate Chamber, photographed here in 1867, arranged to seat over 60 Senators. The gallery has the capacity to seat about 1,200 people.

According to Engle, the House's number 435 was developed only in the Reapportionment Act of 1924, and there is no reason there can’t be more representatives per state. “All Congress would need to do is, as it did in ’24, decide ‘hmmm, that seems a good number for today’ and divvy up the congressional districts accordingly,” he says. “ So one change people rarely consider when they discuss structural change in D.C….would be to enlarge the House, giving the more populous states more power.”

The Senate pays the vice president’s salary.

Article I, Section 3 gives one power to the vice president: “The Vice President of the United States shall be President of the Senate, but shall have no Vote, unless they be equally divided.” The Senate pays the vice president’s salary, as the veep presides over the body, and, since 1789, 268 tie-breaking votes have been cast. The record, 31, goes to John Calhoun, vice president under John Quincy Adams and Andrew Jackson. He’s followed by John Adams, the first U.S. vice president, with 29.

Congress has seen many ‘firsts.’

Speaker of the House Nancy Pelosi, 2007
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Speaker of the House Nancy Pelosi speaks during the first session of the 110th US House of Representatives on January 4, 2007.

From the first former president to serve as a senator to the first woman to serve as speaker of the House, here are some notable moments in legislative branch history:

  • First African American representative: Joseph Rainey (R-S.C.). Taking office in 1870, Rainey, born into slavery, was also the first African American to preside over the House.
  • First former president to serve as a representative: John Quincy Adams. The sixth U.S. president, serving from 1825 to 1829, took office in the House in 1831. Earlier, he was elected a senator in 1802.
  • First Hispanic American representative: Joseph Marion Hernández. Elected in 1822 as a Delegate from Florida to the 17th Congress, Hernández served for less than one year in the House.
  • First former president to serve as a senator: Andrew Johnson. Serving as the 17th U.S. president, he was sworn in 1865 following the assassination of Abraham Lincoln. Previously, he served five terms in the House beginning in 1843, became governor of Tennessee in 1853, and was a senator in 1857. He returned to the Senate in 1875, dying that same year. Johnson is also the first president to be impeached.
  • First first lady to be elected senator: Hillary Clinton (D-N.Y.), while serving as first lady, she took office in 2001. She’s also the first woman to be named presidential nominee by a major U.S. political party.
  • First congressman to represent two states: Daniel Hiester, an Anti-Administration and, later, Republican candidate, served as a representative for Pennsylvania from 1789-1796 and for Maryland from 1801-1804.
  • First senator to represent three states: James Shields, an Irish immigrant, served as senator for Illinois from 1849- 1855, Minnesota from 1858 to 1859, and Missouri in 1879. He remains the only senator to serve three states.
  • First woman to serve as representative: Jeannette Rankin (R-Mont.). A suffragist, Rankin is also the only member of Congress who voted against U.S. entry into WWI and WWII.
  • First woman to serve as senator: Rebecca Felton (D-Ga.). At age 87, Felton was appointed to fill a vacancy in 1922, serving a mere 24 hours in a symbolic move. Hattie Caraway (D-Ark.) was the first woman elected as senator in 1932.
  • First female speaker of the house: Nancy Pelosi (D-Calif.). First elected speaker in 2007, Pelosi was reelected to the position in 2019.