Americans have spoken, and their collective voice has summoned for change.

After years of ads, infomercials, primaries, debates and an online campaign that generated a groundswell of support among the nation's disaffected youth, Democratic presidential nominee Barack Obama has defeated the Republican pick for president, Arizona Senator John McCain. The junior senator from the state of Illinois announced his candidacy 22 months ago, beginning his historic, barrier-busting bid for the nation's highest office.

CNN called the election for Obama at 11 p.m. ET, as the polls closed on the West Coast. He will be America's 44th president.

Obama is projected to receive enough electoral votes to pass the 270-vote threshold needed to secure the office. CNN projects he'll take California, Washington, Oregon and Hawaii when all is said and done.

During an event held in Chicago's Grant Park, attended by 100,000 Obama supporters, the nation's newly elected leader vowed to be honest about the challenges the country will face in the coming months and years. "The road ahead will be long," he said. "Our climb will be steep. We may not get there in one year or even one term, but America — I have never been more hopeful than I am tonight that we will get there. I promise you: We, as a people, will get there."

In his concession speech, McCain graciously accepted defeat, telling the faithful mass gathered in Phoenix that his words marked the end of a long journey. "I pledge to [Obama] tonight to do all in my power to help him lead us through the many challenges we face," McCain told the crowd. "Today, I was a candidate for the highest office in the country I love so much, and tonight, I remain her servant."

No matter how the vote ended up, history was going to be made Tuesday (November 4). A victory for one ticket would have given the United States its oldest first-term president (McCain, who is 72) and first female vice president (Alaskan Governor Sarah Palin). The other would see the first African-American (Obama) moving into the White House and the first Roman Catholic (Senator Joseph Biden) to win the vice presidency. It also marks the first time two sitting senators vied for the post and the first time both major candidates were born outside the continental U.S. Obama was born in Hawaii, while McCain was born in the Panama Canal Zone.

But, ultimately, it was Obama who swept in to take the White House, netting some huge, unexpected wins early Tuesday evening. CNN called the ever-important battleground states of Pennsylvania (where McCain canvassed heavily in the final days of his campaign); Ohio (where voter turnout was estimated at more than 80 percent); and Virginia for Obama, which effectively spelled doom for his rival. Ohio was a seismic victory for Obama, considering the state's 20 electoral votes were critical to President Bush's re-election in 2004, and no Republican has ever won the White House without winning Ohio first.

The Center for Information and Research on Civic Learning and Engagement, also known as CIRCLE, which promotes research on the civic and political engagement of Americans between the ages of 15 and 25, claims that voters between the ages of 18 and 29 represented 18 percent of all voters Tuesday. That's one point higher than in 1996, 2000 and 2004, when young voters represented 17 percent of voters. More precise data on the youth share of the vote will be released Wednesday.

Obama also took Virginia, marking a historic shift in the state that was more than 40 years in the making. The last time Virginia voted for a Democrat was back in 1964, when President Lyndon B. Johnson was elected. Recent shifts in the state's demographics are believed to have helped Obama secure the win. The last two gubernatorial elections were won by Dems, as were the last senatorial elections.

Voter turnout in the traditionally conservative state was massive, with 500,000 young people registering to vote in this year's election. Heading into Tuesday's election, Obama was leading McCain by 9 percentage points and will now claim the state's 13 electoral votes.

MTV News is at the polls in all 50 states — check out our coverage all day long on MTV and right here on MTVNews.com. Then, tell us why you voted! Comment below, upload video at yourhere.mtv.com, or text VOTE to 66333 with your first name, age, state and a comment about your experience. Your message will appear on our election map and could appear on TV today!

[This story was originally published at 11:26 pm E.T. on 11.4.2008]