Some people cried. Others became flustered. One wore an Obama flag as a cape and a hat emblazoned with his name.
"We just praise and thank the Lord," said one woman who came face to face with Obama in the White House's Blue Room. "It's been better than we expected."
Obama and first lady Michelle Obama stood under a crystal chandelier as a steady stream of visitors made it to the first-floor formal room in the mansion. Some guests wore coats and scarves, a reminder of the cold they braved to see Obama just one day after he became the 44th president.
"Enjoy yourself, roam around," a smiling Obama told one guest as he shuffled through the room. "Don't break anything."
Several women, including Christine Easterling, broke down in tears when they met the Obamas.
"It was overwhelming," Easterling said as she left the room. She said she had volunteered for the presidential inaugural committee. "We worked so hard and got this."
The crowd included inauguration volunteers, random guests and those selected by an Internet lottery.
One woman told Michelle Obama that she and her family were beautiful. The first lady asked that the guest stop, otherwise she would start to cry and smear her makeup.
Barack Obama shifted in the formal room as journalists along the rear wall snapped pictures. Even a meet-and-greet event now included more than a dozen journalists to capture the scene.
Obama's aides announced the open house to promote their themes of an open and accessible White House. President Bill Clinton had a similar even the day after his 1993 inauguration.
Vice President Joe Biden and his wife, Jill, also invited visitors -- Washington public school children -- to their official residence at the Naval Observatory.