A "lame duck" session of Congress occurs whenever one Congress meets after its successor is elected, but before the term of the current Congress ends. Under present conditions, any meeting of Congress after election day in November, but before the following January 3, is a lame duck session. Prior to 1933, when the 20th Amendment changed the dates of the congressional term, the last regular session of Congress was always a lame duck session. Today, however, the expression is used not only for a separate session of Congress that convenes after a sine die adjournment, but also for any portion of a regular session that falls after an election.A lame duck session can occur in several ways. (1) Congress has usually provided for its existing session to resume after a recess spanning the election. (In 1954, only the Senate returned in this way, while the House adjourned sine die.) (2) In 1940, 1942, and also most recently in 2008, 2010, and 2012, at least one house continued meeting in intermittent, or pro forma, sessions during the period spanning the election (in these most recent years, the Senate used this means to forestall recess appointments). (3) Congress can reconvene after an election pursuant to contingent authority granted to the leadership in a recess or adjournment resolution (the House followed this course in 1998 and 2008). Two other possibilities have not been realized: (4) Congress could set a statutory date for a new session to convene after the election, then adjourn its existing session sine die. (5) While Congress is in recess or sine die adjournment, the President could call it into extraordinary session at a date after the election.Congress has held 19 lame duck sessions from 1940 through 2012. In these years, election breaks usually have begun by mid-October, and typically lasted between one and two months. Congress has typically reconvened in mid-November and adjourned before Christmas, so that the lame duck session lasted about a month. Yet election breaks have begun as early as August 7 or as late as November 3, and ended as early as November 7 or as late as December 31. Lame duck sessions have ended as early as November 22 and as late as January 3, and have extended over as few as one, and as many as 145, calendar days. Usually, however, each house has actually met on 8-24 days during these lame duck sessions (including pro forma sessions). Although between 1994 and 2006, each house met in session for fewer than 12 days, the three most recent lame duck sessions were considerably longer, lasting an average of 17 days in the House and 27 days in the Senate.