Members of the House of Representatives are apportioned among the states according to their populations in the federal census. Every state is entitled to at least one representative. States that are entitled only to one (currently Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming) have a representative at large, i.e., one elected by the whole state. The legislatures of those states entitled to more than one representative have been required since 1842 to divide their states into congressional districts. Representatives are chosen for two-year terms, and the entire body comes up for reelection every two years. A representative must be 25 or older, a U.S. citizen of at least seven years standing, and a resident of the state in which he or she is elected. Although without a vote (except on the committees on which they serve), one resident commissioner from Puerto Rico (elected for a four-year term) and one delegate each from the District of Columbia, American Samoa, Guam, and the U.S. Virgin Islands (elected for two-year terms) sit in the House. The presiding officer of the House, the speaker, is elected by the members of the House and may designate any member of the House to act in his absence. In 1910 a revolt against the powerful speaker, Joseph Gurney Cannon, resulted in the transfer of much of the power and influence of that office to the House committees. The reforms of the mid-1970s, however, modified seniority rules and gave committee members and the speaker more powers, and changes introduced in the mid-1990s by the Republicans further reduced the influence of seniority and concentrated more power in the speaker and other members of the majority leadership.

The most important responsibility of Congress is that of making the laws of the United States. In both houses the work of preparing and considering legislation is done by standing committees, and in addition there are special committees in each house as well as joint committees with bicameral membership. The two houses have an equal voice in legislation, but revenue bills must originate in the House of Representatives. Bills, after having been passed by each house separately, must be signed by the president of the United States within 10 days of their submission, or they become law automatically, unless Congress is not in session. If vetoed by the president, a bill may become law only by its repassage by a two-thirds majority in each house. The Constitution requires a regular annual meeting of Congress, which, since the passage of the Twentieth Amendment in 1933, begins on Jan. 3 each year. The president may call an extra session of Congress or of either house. The proceedings of each house are recorded in the Congressional Record.

Only the House of Representatives may impeach the president or other federal officers and the Senate alone has the authority to try impeachments, but each house is the judge of the qualifications of its own members. The Senate must ratify all treaties by a two-thirds vote and confirm important presidential appointments to office, including cabinet members, judges of federal courts, and high-ranking officers of the armed forces. Because of this and because it is the smaller body and its members enjoy longer terms of office and virtually unlimited debate, the Senate is regarded as the more powerful of the two houses.

Congress, as a whole, reached the zenith of its power during Reconstruction. Throughout its history many critics have charged that Congress operates under antiquated machinery and processes that are inadequate. Procedural reforms proposed have included the adoption of a rule of relevancy in Senate debate, employing joint hearings on similar bills, liberalizing the methods by which a bill may be discharged from committee for consideration, and abolishing seniority as the basis for committee chairmanships.

See R. Dadson, The Role of the Congressman (1969); N. W. Polsby, Congress and the Presidency (2d ed. 1971); L. Fisher, President and Congress (1972); A. Clausen, How Congressmen Decide (1973); J. Kingdon, Congressmen's Voting Decisions (1973); R. Goehlert and J. Sayre, The United States Congress (1981); J. L. Sundquist, The Decline and Resurgence of Congress (1981); M. A. Peterson, Legislating Together: The White House and Capitol Hill From Eisenhower to Reagan (1990); D. R. Mayhew, Divided We Govern (1991).