Size of House and Senate
Why do we have 100 Senators and 435 Members of the House? Can these numbers be changed?
The number of Senators is set by the Constitution and cannot be changed without amending that document. The size of the Senate is established by Article I, section 3 of the Constitution, which states: "The Senate of the United States shall be composed of two Senators from each State . . . " The Senate has had 100 Members since the admission of Hawaii into the Union in 1959.
The number of Representatives is set by statute and could be changed with the passage of a new public law. The House has had 435 Members since 1911, when concerns over space and the quality of deliberations among so many representatives led to the establishment of a membership cap.
Section 2 of Amendment XIV to the Constitution states that "Representatives shall be apportioned among the states according to their numbers. . . " Various rulings of the Supreme Court over the years have interpreted this to mean Congressional districts should have as equal a population as possible. The Constitution also states that each state shall have at least one Representative, no matter how small its population.
Because of the Constitutional requirement that equity be maintained in the population size of each district, state legislatures must reapportion their state's population by redrawing congressional district lines every 10 years, after the results of the national Census are known. Based on the 2000 Census, the 435 statutory cap on membership in the House means each Representative has, on average, close to 650,000 constituents.
The state with the largest population, California, has 53 Representatives in Congress, while seven states with small populations have only 1 Representative for the entire state. The states with so-called "At Large" Representatives are: Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming.
Once the 2010 Census has been completed, another round of apportionment will begin. You can find the data used for reapportionment after the 2000 Census on the U.S. Census Bureau congressional apportionment website.
As the size of the constituency each Member must represent has steadily increased since then, there has been some discussion about increasing the overall size of the House of Representatives. However, more Members would also mean expanding existing office buildings and perhaps even necessitate renovations to the House chamber in the Capitol. Given the cost-conscious environment surrounding Congress in recent years, and especially now, it is unlikely that proposals to spend additional money on Congress itself would be seen as politically viable at this time.
When Congress began in 1789, there were only 65 Members in the House, and 26 in the Senate. The original 65 Representatives each had just over 30,000 constituents.
Larry Sabato, Director of the University of Virginia’s Center for Politics, has written an excellent piece advocating for an increase in the size of the House of Representatives, in order to lower the Member-to-constituent ratio. You can read it on the website of “Democracy, a Journal of Ideas."