The National Park Service will put out an "official" crowd count in two or three days after studying aerial photography.
The immense security and law enforcements arrayed throughout Washington, D.C., have not reported any major problems.
Although the FBI and Department of Homeland Security issued a security bulletin earlier today, law enforcement officials tell CBS News there are no credible threats to the inauguration.
A small number of medical issues have been reported. The D.C. Metro Fire Department tells CBS News it has gotten 94 medical calls and made 30 transports throughout the day.
UPDATE 5:30 p.m.: Law enforcement officials are reporting no inauguration related arrests yet.
D.C. Metro Police Department Spokesman Traci Hughes tells CBS News MPD has made "no arrests" today -- "None."
The U.S. Park Police, which has jurisdiction over the National Mall, also tells CBS News that it did not make any arrests either.