Article One of the United States Constitution describes the powers of Congress, the legislative branch of the federal government. The Article establishes the powers of and limitations on the Congress, consisting of a House of Representatives composed of Representatives, with each state gaining or losing representation in proportion to its population, and a Senate, composed of two Senators from each state. The article details the manner of election and qualifications of members of each House. It outlines legislative procedure and enumerates the powers vested in the legislative branch. Finally, it establishes limits on the powers of both Congress and the states.
There are ten sections in the article. The Vesting Clause (Section One) vests "all legislative powers herein granted" to the Congress. Section Two deals with the House of Representatives, setting its composition and two-year term for representatives, providing for the qualifications of members, establishing that Representatives and direct taxes "shall be apportioned among the several States...according to their respective Numbers," requiring a decennial Census, providing for state governors to set special elections to fill vacancies, establishing that the House shall choose its own speaker and other officers and have the sole power of impeachment. Section Three deals with the Senate, setting its composition, a six-year term for members, and a procedure to begin a staggering of elections so that roughly one-third of Senators are elected every even-numbered year. The section also provides for governors to fill vacancies temporarily by appointment before an election is held, sets qualifications for Senators, provides that the Vice President of the United States shall be President of the Senate but shall have only a tie-breaking vote, provides for the Senate to chose its own president pro tempore and other officers, and giving to the Senate the sole power of the trial of impeachments.