Updated

President Barack Obama was greeted by an enthusiastic crowd along his inauguration parade route Tuesday, and he stepped out of his limousine along the way to wave to the throng of cheering supporters before entering the reviewing stand.

As the Obama family soaked in the historic moment, they watched the conclusion of the inaugural parade outside the White House, hours after Obama had addressed his fellow Americans for the first time as president of the United States.

Re-enactors from a black Civil War regiment; World War II's surviving Tuskegee Airmen; Freedom Riders from the civil rights movement all marched. They were Obama's nod to the past among 13,000 parade participants from all 50 states scheduled to travel down Pennsylvania Avenue from the Capitol to the White House.

About 15 minutes into the parade, Obama and his wife, Michelle Obama, had stepped out of the limousine with a USA 1 license plate to rousing cheers and greeted part of the enthusiastic crowd. A couple of moments later, Vice President Joe Biden and his wife, Jill, joined them on the walk -- to the loud cheers of hundreds of people who had packed onto rooftops and balconies.

The Obamas walked a few blocks before getting back into the car but emerged again as the limousine neared the parade reviewing stand in front of the White House. Next they will head out to a string of 10 inaugural balls that are expected to last well past midnight.

Earlier in the day, there had been some unexpected drama on Capitol Hill. Sen. Ted Kennedy, D-Mass., was taken to the hospital after suffering what doctors later said was a seizure brought on by "simple fatigue." He went into convulsions during Obama's celebratory inaugural luncheon, and was taken out on a wheelchair.

West Virginia Sen. Robert Byrd, 91, also in failing health, reportedly was "emotional" at the time of the collapse and security detail decided to remove him from the room as a precautionary measure. But Byrd spokesman Mark Ferrell said the West Virginia Democrat's departure was not linked to a medical issue.

Along the 1.7-mile parade route, many of the joyous but frozen onlookers had lined up before dawn to secure a good vantage point of Obama's motorcade and the following two hours of pageantry. People peered from the windows of nearly every building.

"He's the people's president," Patricia Correia, 68, of Lancaster, Calif., said. "He would not be the type to sit here in the car. He knows that we waited out here this long."

At 15th Street and Pennsylvania Avenue, most people cleared the bleachers immediately after Obama walked past, not even waiting for the Bidens, who walked much of the parade route.

At points along the route, spectators bundled in parkas and blankets were 10 deep, and at one spot people danced in place to the "Electric Slide" to keep warm in temperatures that stayed just below freezing. When the parade started at 3:35 p.m., the temperature had dropped to 27 degrees. Chilly, but far from the record of minus 2 degrees at Ronald Reagan's second inauguration in 1985.

"I came because it's about us making history," said Latori Brown, a 21-year-old black woman from Sumter, S.C., who'd been waiting since dawn and shivered under a blanket. "I'm not worried about the cold. It's worth it."

The Associated Press contributed to this report.