"This is a monumental moment in our nation's history," Martin Luther King III, the civil rights icon's oldest son, told the Associated Press on Wednesday. "And it becomes obviously an even greater moment in November if he's elected."
Clinton's move during the roll call had been carefully orchestrated. As she spoke, the red digital clock that times speakers was counting down to zero.
Her arrival on the convention floor, where she stood out in a turquoise pantsuit under the light of TV cameras, brought a roar of cheers. "That's class!" said Vincent Arriola, a delegate from Guam.
There also were tears. Pilar Lujan, a senator from Guam, had hoped this would be a year she would "see a woman rule the nation."
"The sportsmanship of Hillary Clinton really made women even greater," she said.
Montana state Sen. Carol Williams, who called Clinton "my friend" as she announced her state's vote, said the New York senator's performance helped reconcile her supporters to Obama's nomination.
"She's been so elegant and courageous," Williams said.
Delegates had been signing their ballots all day, bringing to an end a drama that had been running since the last Democratic nominating contest on June 3.
Earlier in the day, Clinton had released her delegates, allowing them to vote for either candidate. She told them that she had voted for Obama but did not tell them how to vote.
Mark Smith, a delegate from Silsbee, Texas, changed his vote as a result. "When Barack became her candidate, he became mine. It was difficult because it was a bitter battle between two qualified, very talented candidates for presidency."
'He's my No. 1 now'
The long march toward unity may finally have ended for the Democrats with Wednesday's roll call, but given the deep passion, and anger, of Clinton's supporters, it might not.
"It's going to take me awhile, because I've been supporting her so long," said Clara Maynard, a Texas delegate. "But I intend to vote for Obama. I intend to put an Obama sign in my yard and a bumper sticker on my car and to work for him so we can win this election."
"He wasn't my No. 1 candidate, but he's my No. 1 candidate now, because he's going to make a difference in my life," said Arika Kulhavy, a Texas delegate, who noted that she will turn 25 this year and therefore lose her health insurance and her graduate school scholarship, both of which she gets through her father, a college professor.
Going into the roll call, delegates were eager, if not determined, to cast their votes for Clinton.
"It's who we represent, who elected us. We represent the 18 million voters out there. Our vote is their voice. All of us are pretty passionate about that and feel that it's not over until then," Oregon delegate Jane Quinn said. "After that, then we get to step back and then move forward and help elect a Democrat into the White House."
Susie Tompkins Buell, a top Hillary Rodham Clinton fundraiser from the Bay Area, said she had considered not coming to the convention because she was "heartsick" that Clinton was not Obama's vice presidential choice.
She listened to Clinton's speech on Tuesday feeling "deeply sad and incredibly proud." But she said it helped her to come to terms with reality.
"We just have to move on, and I understand that, and I am supporting Obama," Tompkins Buell said. "The sense of urgency was made very, very clear. The party is unified."
Both factions in the party knew all along that the convention would make history.
Mary Ann Andreas, 63, vice chairwoman of the Morongo Band of Mission Indians, was overcome with emotion amid a thundering aPepsi Center as Obama was officially nominated.
"I think it will change America in more ways than anyone realizes yet," said Andreas, a member of the Democratic convention's credentials committee.
"Once we get past that threshold of the first black president, it will throw off many chains that bind us and make us the great country we were meant to be," Andreas said.
Contributing: Fredreka Schouten, Kathy Kiely, Garrett Hubbard and Julie Wolf