(CNN) -- It was a moment Howard Hemsley thought might never come.
"If three years ago, someone had said to me on the streets of New York that somebody named Barack Obama would be our nominee, I would have said they were crazy," said Hemsley, an African-American delegate from New York. "I volunteered for him for two years, and most of that time I never thought he would win."
Yet Hemsley was just a few yards from Sen. Hillary Clinton as she moved that Obama be named the Democratic presidential nominee by acclamation, before a cheering stadium of delegates at the Democratic National Convention on Wednesday.
"This is something people like me have been waiting for for days, weeks. Years," he said with tears in his eyes. "He's going to the White House. He's going to be our next president." Watch Obama clinch the historic nomination »
Hemsley was one of many caught up in the frenzy of emotions after delegates seconded Clinton's movement and cheered Obama into history. Tears of joy and sadness accompanied the jubilant scene, and many attendees struggled to find the words to express their emotions.
It was an event Henry March thought he'd never live to see.
"I was overcome by joy," said March, a civil rights attorney. "This is one of most significant events in American history."
Others reflected upon the civil rights journey that had led up to Obama's nomination.
"I think about all the suffering, all the pain all the hurt of so many people," said Rep. John Lewis.
"What you see happening here tonight is the down payment of the fulfillment of dream of Martin Luther King," he said. "Just a few short years ago in Georgia, Alabama, Mississippi, many people of color could not even register to vote and now, these people are voting for an African-American."
"It was an amazing moment -- not for African-Americans -- for Americans," CNN contributor Roland Martin said.
"I wanted to be on the floor, not only as a Democrat, as an American, but clearly as an African-American. When I was a little girl, I never thought I'd see this day. I never thought I'd see a viable female candidate, viable minority candidate get this far," CNN contributor and Democratic strategist Donna Brazile said. iReport.com: Are you in Denver? Share sights, sounds
"When we were kids, our parents would tell us we could grow up to be anything we wanted to be. We giggled because we knew certain doors were closed. After this historic year, those gates are now wide open. So this is an exciting moment for the entire country," she said.
Even Republicans in the audience felt the drama of the moment. "I was deeply moved and I think that you'd have to be a curmudgeon if you don't see the historic nature of this evening, GOP conservative analyst Amy Holmes said.
"It is a milestone that we witnessed here tonight in our country's ability sometimes to just say, you know, the past is the past," CNN senior political analyst Gloria Berger said.
Avis Johnsonhel of Memphis, Tennessee, said she still could not believe that Obama could win the election. "Look how hard he had to fight just to win the nomination," she said. "It's not just Democrats that are going to vote in this election. I want to think he can win, but I live in the real world."
The extraordinary nomination began with the otherwise routine act of the roll call, in which delegates cast their vote for presidential nominee.
Some delegates voted for Clinton, but Rep. James Clyburn said he felt momentum gathering when the delegates from Arkansas, a stronghold for Clinton, cast all 47 of their votes for Obama.
"It's demonstrating that this party has come together and we're going to be a united group," said Clyburn. "We have taken a large step toward reconstruction in this country."
Obama will speak on Thursday in Denver, Colorado, on the anniversary of King's "I have a dream" speech.