An inauguration planning official says turnout was "definitely above 800,000" and possibly up to one million people.
Chris Geldart, who directs the District of Columbia's homeland security and emergency management agency, says early and unofficial estimates of the number of people on the National Mall indicate a turnout higher than 800,000. That's based on aerial views of how the crowd filled sections of the mall.
Officials initially anticipated as many as 800,000 visitors, but lowered the projections to 500,000 to 700,000, based partly on an updated number of charter buses and restaurant and hotel reservations.
But Geldart, who's also co-chairman of the district's presidential inaugural committee, said the event benefited from relatively mild weather.
About 1.8 million people attended President Barack Obama's first swearing-in in 2009.