Clinton and Obama traded victories in an epic struggle with no end in sight. Clinton won Super Tuesday's biggest state, California, in the Democratic campaign, capitalizing on backing from Hispanic voters. Obama fashioned victories in Alabama and Georgia on the strength of black support.
Neither Clinton nor Obama proclaimed overall victory on a Super Tuesday that sprawled across 22 states, and with good reason. Obama won 13 states and Clinton eight plus American Samoa. But with victories in New York, New Jersey and Massachusetts, the Clinton led narrowly in the early tabulation of delegates for the night.
Missouri was so close that although Obama won the vote count it was likely to be hours before it became clear whether he or his rival had captured a majority of the state's 72 delegates.
The Democratic caucuses in New Mexico remained unsettled. Clinton had a 117-vote lead when the party shut down its vote counting operation until 11 a.m. EST.
Polling place interviews with voters suggested subtle shifts in the political landscape.
Overall, Clinton was winning only a slight edge among women and white voters, groups that she had won handily in earlier contests, according to preliminary results from interviews with voters in 16 states leaving polling places.
Obama was collecting the overwhelming majority of votes cast by blacks - a factor in victories in Alabama and Georgia.
Clinton's continued strong appeal among Hispanics - she was winning nearly six in 10 of their votes - was a big factor in her California triumph, and in her victory in Arizona, too.
Clinton won at home in New York as well as in California, Massachusetts, New Jersey, Oklahoma, Tennessee, Arizona and Arkansas. She also won the caucuses in American Samoa.
Obama won Connecticut, Georgia, Alabama, Delaware, Utah and his home state of Illinois. He prevailed in caucuses in North Dakota, Minnesota, Kansas, Idaho, Alaska and Colorado.
The allocation of delegates lagged the vote count by hours. That was particularly true for the Democrats, who divided theirs roughly in proportion to the popular vote.
Overall, Clinton had 760 delegates to 693 for Obama, out of the 2,025 needed to secure victory at the party convention in Denver. Clinton's advantage is partly due to her lead among so-called superdelegates, members of Congress and other party leaders who are not selected in primaries and caucuses - and who are also free to change their minds.
Alabama and Georgia gave Obama three straight Southern triumphs. Like last month's win in South Carolina, they were powered by black votes.
Democrats and Republicans alike said the economy was their most important issue. Democrats said the war in Iraq ranked second and health care third. Republican primary voters said immigration was second most important after the economy, followed by the war in Iraq.
The survey was conducted in 16 states by Edison Media Research and Mitofsky International for The Associated Press and television networks.
Already, the campaigns were looking ahead to Feb. 9 contests in Louisiana, Nebraska and Washington state and Feb. 12 primaries in Maryland, Virginia and the District of Columbia. And increasingly, it looked like the Democrats' historic race between a woman and a black man would go into early spring, possibly longer.
Obama and Clinton spent an estimated $20 million combined to advertise on television in the Feb 5 states.
Obama spent $11 million, running ads in 18 of the 22 states with Democratic contests. Clinton ran ads in 17, for a total of $9 million.