Several journalists have shared these images on Twitter comparing the crowds at Obama's inauguration in 2009 and the crowds today.
Did you know?
Since 1937, U.S. vice presidents are also sworn into office at the same ceremony as presidents. Before that, it was in the Senate chamber. The vice president-elect takes the oath first, too, followed by the president-elect around noon.
Trump gave a thumbs-up just before coming out.
President-elect Donald J. Trump has been announced to the crowd assembled for the inauguration, and was preceded onto the platform by senior Republican leaders.
Vice President-elect Mike Pence has been announced and is on the platform for the ceremony.
That is the last four "ruffles and flourishes" from the Marine band -- to denote the high honor of the presidency -- that Obama will get as president.
Outgoing President Obama and outgoing Vice President Biden have been announced to the crowd.
Our VOA colleagues report that chants of "USA! USA!" could be heard as the huge crowd awaited the start of the inauguration ceremony. But it's very quiet now aside from the announcer and the Marine band as the audience awaits the announcement of Obama and then Trump.
Incoming first lady Melania Trump and Karen Pence have been introduced to the crowd ahead of the ceremony.
As we get ready for the inauguration ceremony to begin, here's video of the meeting at the White House of Trump and Obama with their wives.