The diverse crowd numbered in the hundreds of thousands. Among them was Chicago Mayor Rahm Emanuel.
He says the diversity present at the podium and in the gathering reflects America's new political majority.
"The country is changing dramatically along racial, ethnic, sexual orientation lines, it's just dramatically changing," said Emanuel.
President Obama quoted the constitution generously during his speech, emphasizing the nation's founding principles of equality.
"We, the people, declare today that the most evident of truths--that all of us are created equal," President Obama said.
"This is the United Nations, this is America right here," said Blanche Price, who traveled from Oak Park, Illinois.
"I think it speaks a lot about America, the whole mosaic of America. You see everybody represented here," said Tom Kane, attendee.
Tom and Dee Stapka, who attended the inauguration in 2009, made the long trip to see their hometown hero begin his second term.
"We drove on Friday. We drove... Not fly, we drove. Long drive," said Tom Stapka.
The marching band from Sandwich, Ill., high school performed at one of the inauguration weekend events.
"Seeing the president get signed into office, that's an amazing experience most people don't get to see," said Jacob Brown, school band member.
"It's special because it's once in a lifetime to be able to come out here and witness it in person," Sandwich High School's Sam West said.
Also in Washington was Chicago teacher Timeica Bethel who said grew up in public housing on the city's Southwest Side and went on to attend Yale.
"I'm so excited to be around so many people with similar views and people that are ready for America to move forward and want the same things for our country," Bethel said.
The challenges ahead
After the inaugural celebrations end, Obama must confront the Republican majority in the House of Representatives that includes some very conservative "tea party" members.
"This notion of confrontation in the House: close down the government, close down the economy lurching from one to the other. The American people don't like that," Illinois Senator Dick Durbin (D) said.
Republican Congressman Aaron Schock, a self-described moderate, said Obama's second term could be different from the first.
"We have a lot of challenges facing our country. The election is over and I think they expect us to get things done. We got a lot challenges we've got to solve," Schock said.
Gun control, immigration reform, energy and education policy are among the priorities of the second Obama administration.
Chicago Mayor Rahm Emanuel, the president's first chief of staff in the White House, said the president's very conservative opponents have run out of political steam.
"I think those with a rigid, ideological line of no ground will be marginalized in this process," Emanuel said.