Updated November 4, 2008 at 7:40 p.m.
Barack Obama built a formidable lead in his bid to defeat rival John McCain in a nation clamoring for change. Fellow Democrats took four Senate seats from Republicans, and reached for more.
Obama gained precious ground in Ohio and Pennsylvania. Obama also swept through territory typically friendly to Democrats in the East and Midwest.
The Illinois senator also won Colorado and its nine electoral votes.
Obama led in electoral votes with 175 of the 270 needed to win the White House. McCain had 61.
That left the battlegrounds to settle the race: Florida, Ohio, Virginia and more. Most were customarily Republican, but Obama spent millions hoping to peel away enough to make him the 44th president, and his triumph in Pennsylvania left the Republican with scant room for error.
"May God bless whoever wins tonight," President Bush told dinner guests at the White House, according to spokeswoman Dana Perino.
A jubilant crowd of thousands gathered in Grant Park in downtown Chicago on an unseasonably mild night, confident it would be Obama. They reacted each time Obama was announced the winner in another state - and the cheers were particularly loud when Pennsylvania fell.
The Democrat's states included Colorado, Wisconsin, Michigan, New York, Rhode Island, Minnesota, Pennsylvania, New Hampshire, Vermont, Connecticut, Delaware, Illinois, Maine, Massachusetts, Maryland and New Jersey, as well as the District of Columbia.
McCain had Kansas, Arkansas, Kentucky, Tennessee, Oklahoma, Wyoming, Alabama and South Carolina.
The nationwide popular vote was remarkably close. Totals from 13 percent of the nation's precincts showed Obama with 49.9 percent and McCain with 49.2.
Interviews with voters suggested that almost six in 10 women were backing Obama nationwide, and men leaned his way by a narrow margin. Just over half of whites supported McCain, giving him a slim advantage in a group that Bush carried overwhelmingly in 2004.
The results of The Associated Press survey were based on a preliminary partial sample of nearly 10,000 voters in Election Day polls and in telephone interviews over the past week for early voters.
The same survey showed the economy was by far the top Election Day issue. Six in 10 voters said so, and none of the other top issues - energy, Iraq, terrorism and health care - was picked by more than one in 10.