What does the constitution say about inauguration day

n order to ensure a smooth transition of power, there is a need for a period of time between the election and and the swearing in of the new period.  New presidents have to choose cabinet members and other key administration members, as well as get up to speed on security issues and simply began the task of physically moving a new team to Washington.  For the old president, this time in office is referred to as "the lame duck" period, a term taken from Wall Street that used to refer to people who could not pay off their loans--persons, like the lame duck president, without much capital.