The 20th amendment to the U.S. Constitution, ratified in 1933, specifies that the term of each elected president of the United States begins at noon on January 20 of the year following the election. Each president must take the oath of office before assuming the duties of the position.

Until 1933, Inauguration Day was March 4, in commemoration of the day the Constitution went into effect -- March 4, 1789. This meant, however, that a president voted out of office in November would not leave office until March of the following year.

The 20th amendment shortened this “lame duck” period (when an official continues to serve between the election and inauguration of a successor) by moving Inauguration Day to January 20, two weeks after the Electoral College's votes are certified by the president of the Senate.

The 2005 inauguration of George W. Bush will mark the 55th time that the U.S. president has been sworn in for a four-year term – an unbroken succession since George Washington first took the same oath in 1789. President Bush will take the oath of office on the west front of the U.S. Capitol, overlooking the many monuments on the National Mall, a tradition started by Ronald Reagan in 1981. The swearing-in ceremony has been held outdoors, weather permitting, since the 1817 inauguration of James Monroe.

The location of the swearing-in ceremony has changed throughout the years, moving from the Old Brick Capitol (the current site of the Supreme Court Building) to the east front of the Capitol and then to the west front. Some inaugurations, including George Washington’s, have also taken place outside of Washington, D.C.