Only moments after Vice President Joe Biden was sworn in, the Bush Presidency 's presence on whitehouse.gov dissapeared.
And with the click of the refresh button, the Obama Presidency web platform appeared.
Biden was sworn in at about 11:57 a.m. Eastern Standard Time, and the U.S. Constitution mandates that the presidency must begin at noon.
So even before Obama took the oath of office, he became the commander-in-chief.
The 20th Amendment specifies that the terms of office of the president and vice president "shall end at noon on the 20th day of January ... and the terms of their successors shall then begin."
And so, the transfer of power was complete when the clock struck noon.