December 2, 1793
When should Congress begin its annual session? The 18th-century framers of the United States Constitution, accustomed to an agriculturally based economy with its cycles of planting, growing, and harvesting, considered the mostly dormant month of December to be a particularly good time for senators and representatives to begin their legislative sessions. Consequently, Article I, Section 4 of the United States Constitution states that "The Congress shall assemble at least once in every year, and such meeting shall be on the first Monday in December, unless they shall by law appoint a different day.”
Then, in September 1788, after the necessary three-quarters of the states had ratified the Constitution, the existing Congress under the Articles of Confederation passed a law setting March 4, 1789, as the convening date for the First Federal Congress. March 4 thereby became the starting point for members’ terms of service, while the first Monday in December remained as the constitutional start date for each legislative session.
The First Federal Congress did indeed meet on March 4, 1789 (although it did not achieve a full quorum until April), but as that first two-year Congress came to a close, members decided that the Second Congress would convene several weeks early, on October 24, 1791. Not until the Third Congress met on December 2, 1793, did the Senate and House of Representatives firmly adopt the Constitution’s "First Monday in December" timetable.
For the next 140 years, Congress followed this pattern, although presidents, facing national emergencies or other "extraordinary occasions," exercised their constitutional prerogative to "convene both Houses, or either of them," on another date when necessary. Outgoing presidents often used this provision to call the Senate into a brief session at the March 4 start of their successor’s term, for example, to confirm cabinet and other key executive nominations.
In 1933, following a long reform effort to modernize the congressional schedule, the nation ratified the Constitution’s Twentieth Amendment, setting January 3 as the annual meeting date for Congress. Known as the “Lame Duck Amendment,” this change shortened the period between election and start of service for members of Congress and set a schedule better suited to the needs of the modern Congress.