Which amendment changed the lame-duck period for elected officials?

The amendment that changed the lame-duck period for elected officials is the 20th Amendment. Ratified in 1933, this amendment significantly altered the timeline for when new members of Congress and the President and Vice President take office.

Prior to its ratification, elected officials often faced a lengthy period between the election in November and taking office in March, during which outgoing officials, or "lame-duck" officials, continued to serve. This delay often led to inefficiencies and a gap in leadership during critical transitional periods. The 20th Amendment reduced this period, moving the start date for Congressional sessions to January 3rd and the inauguration of the President to January 20th.

This amendment was designed to mitigate the issues associated with the lame-duck period, allowing incoming officials to assume their responsibilities more promptly, which can lead to a more effective government and smoother transitions of power.