Final answer:
The date change for the beginning and end of congressional terms to January 3rd was established by the Twentieth Amendment, also known as the "Lame Duck Amendment".
Step-by-step explanation:
The change of the date on which congressional terms began and ended from March to January 3rd was implemented by the Twentieth Amendment of the United States Constitution. This amendment is sometimes referred to as the "Lame Duck Amendment" because it reduced the amount of time lame-duck members of Congress and the President stayed in office after an election. The Twentieth Amendment was significant not only for shifting the start and end of congressional terms but also for moving the presidential inauguration date, and for establishing a clearer line of succession.
According to the text of the amendment, "The terms of Senators and Representatives at noon on the 3rd day of January, of the years in which such terms would have ended if this article had not been ratified, and the terms of their successors shall then begin." This established a new uniform start date for the newly elected Congress and ensured a more systematic transition of power.