The generation gap also presented itself within the GOP results. Those under 45 went 39 to 22 percent for Mike Huckabee.
After the New Hampshire primary, the race moves to Michigan.Iowa entrance poll results
Obama's win was substantial: 38 percent, compared to 30 percent for former Senator John Edwards and 29 percent for Senator Hillary Clinton.
The margin was similar on the Republican side: Mike Huckabee got 34 percent versus 25 percent for former Governor Mitt Romney and 13 percent each for former Senator Fred Thompson and Senator John McCain.
"We are one nation. We are one people, and our time for change has come," Obama said.
On just about every measure, Obama's message resonated with Democratic caucus-goers in Iowa, who, according to entrance polls conducted for the television networks, considered 'change' the most-desired candidate attribute versus experience and empathy.
The Democratic turnout was nearly double that of 2004 and Obama persuaded young voters and independents to flood gyms and church basements in record numbers.
He won the "change voters" 2-1 over Senators John Edwards and Hillary Clinton and grabbed 57 percent of the support of those under 30.
Even women, long considered Clinton's bulwark, chose Obama over Clinton, 35 to 30 percent. Among men, he did better still, receiving 35 percent to 24 percent for Edwards and 23 percent for Clinton.
Anyone could vote in the caucus and Clinton and Obama were even among self-identified Democrats. But Obama led among the one-fifth of Democratic participants who consider themselves independents, a dynamic that will be much more in play in New Hampshire, where 44 percent of registered voters are independents.
On a night of remarkable results, Obama won white voters 33-27 percent over Clinton. Iowa is 93 percent white.
Religion was the key prism to consider in the Republican caucuses and evangelicals and those calling themselves Christian handed former Arkansas Governor Mike Huckabee a substantial win over Mitt Romney. Thirty-six percent said it mattered "a great deal" that a candidate share their religious belief, and Huckabee won well over half of them: 56 percent. Romney and Senator John McCain each got 11 percent.
Romney, who campaigned the longest and spent the most in Iowa, had the support of those looking for experience and White House 'winnability.' But, as a group, those voters were dwarfed by evangelicals and others most concerned with religion.
