Obama won Pennsylvania's 21 electoral votes, which McCain's campaign had specifically targeted as key to winning the race. Obama did so by doing better than John Kerry in 2004 in central and northern Pennsylvania, an Obama campaign staffer told ABC News' Jake Tapper.
Like voters throughout the nation, the majority of Pennsylvanians said in exit polls that they were very worried about the economy.
"The real surprise here is that John McCain did it as close as he did," Mark McKinnon, a media consultant to McCain in the primaries, told ABC News Tuesday night. "He made this race close, which was amazing, but when the economic meltdown happened, this race just sort of ran away from him."
Exit polls also revealed that Obama made inroads among white men and did well in the state among white women -- a demographic that NPR's senior political analyst Juan Williams said Tuesday on "Good Morning America" would be critical to McCain's effort.
"John McCain needs those women in Pennsylvania, Ohio and Missouri to come out in big numbers and support him and they've got to break his way if he has a chance today," Williams said.
In Ohio, Obama won the state's 20 electoral votes that proved so devastating in Kerry's loss in the 2004 presidential election. In doing so, Ohio voters continued their streak, selecting the winner in the 12th straight presidential race.
No Republican has ever won a presidential election without carrying the state, and Tuesday night was no exception. Since the last presidential election, there were indications Ohio voters had grown increasingly wary of Republican leadership. In 2006, the election of Democratic Gov. Ted Strickland ended a 16-year Republican hold on the governor's mansion and Democrats won races for U.S. Senate, attorney general, secretary of state and treasurer.
After spending millions of dollars and investing countless hours and energy in the battleground states, the presidential contenders raced through the most critical states of the 2008 race in the final days of the campaign.
Their final pushes topped off far more extensive efforts in the battlegrounds. The campaigns held a staggering number of events in those states since wrapping up their respective party nominations this spring and summer. According to ABC News' count, Ohio ranked first on that list, hosting 145 events between the two tickets through Nov. 4. Florida took a close second, with 113 events, and Pennsylvania ranked third with 101 events through Election Day.
In the end, the battlegrounds fell as follows:
Battlegrounds That Were Leaning Republican:
Georgia: 15 Electoral Votes, Projected Winner: McCain
West Virginia: 5 Electoral Votes, Projected Winner: McCain
North Dakota: 3 Electoral Votes, Projected Winner: McCain
Montana: 3 Electoral Votes, Projected Winner: McCain
Battlegrounds That Were Leaning Democrat:
Virginia: 13 Electoral Votes, Projected Winner: Obama
Pennsylvania: 21 Electoral Votes, Projected Winner: Obama
Wisconsin: 10 Electoral Votes, Projected Winner: Obama
New Hampshire: 4 Electoral Votes, Projected Winner: Obama
Colorado: 9 Electoral Votes, Projected Winner: Obama
Minnesota: 10 Electoral Votes, Projected Winner: Obama
New Mexico: 5 Electoral Votes, Projected Winner: Obama
Iowa: 7 Electoral Votes, Projected Winner: Obama
Nevada: 5 Electoral Votes, Projected Winner: Obama