WASHINGTON -- As Americans go to the polls today, they will bring down the curtain on an election more passionately and tightly contested than ever before -- with the possible exception, of course, of the one just four years ago.
And as they watch the results unfold tonight in a race in which the outcome is anybody's guess, the nation's voters should look for the same trends and indicators that the candidates' respective campaigns will be watching.
First of all, watch Pennsylvania.
Both the Bush and Kerry campaigns see Pennsylvania as a key early indicator of how the night might go, but they are quick to note that this is an election that may remain uncertain until Hawaii weighs in.
As each side claws toward the necessary 270 electoral votes, some analysts said resolution could boil down to the very last state to report: Hawaii's polls don't close until 11 p.m. EST.
Or, of course, even later, given the legions of lawyers already deployed across the nation and the allegations already made in multiple states of voter intimidation or worse.
President Bush is counting on an unprecedented Republican get-out-the-vote drive. Sen. John F. Kerry is counting on the same from Democrats, especially from young voters casting their first ballots.
Besides Pennsylvania, watch Florida and Ohio. Conventional wisdom holds that whoever takes two or three of them is poised for victory. George W. Bush did it in 2000, winning Florida and Ohio.
Minnesota, Wisconsin and Iowa are other major battlegrounds. Al Gore carried all three in 2000, but the margins in Wisconsin and Iowa were less than 6,000 votes each.
Wisconsin looks like the best indicator, and certainly the most volatile: According to surveys by three different polling groups in the last six days, Kerry has either a 7-point lead, a 4-point deficit or a 2-point advantage.
New Hampshire, New Mexico, Nevada and Hawaii could also play big roles.
In 2000, Bush carried New Hampshire and Nevada; Gore, New Mexico and Hawaii. A Bush loss in New Hampshire could be an early indicator that the night is not going his way.
All eyes this time around will be on Florida, the epicenter of the 2000 electoral debacle, but longtime observers say that other states, notably Pennsylvania, may be more indicative of how the election will go.
"If Bush wins Pennsylvania, I think it's over," said Terry Madonna of Franklin and Marshall University, director of the Keystone Poll in that state. "In my lifetime, I can't imagine Pennsylvania going Republican and Ohio going Democratic; it's a calculus that wouldn't even enter my mind. And if Kerry wins Ohio, I don't know how Bush wins, because if Bush loses Ohio, I don't know how he wins Wisconsin or Minnesota."
Madonna said that in his view, "Florida is more of a mystery. It could go either way and not be significant for the election."
Pennsylvania should also prove an early indicator of the parties' success with get-out-the-vote efforts. The Democrats are looking to run up a Kerry margin of at least 385,000 in the City of Philadelphia, up from 345,000 for Gore four years ago, while Republicans have been organizing for months to be competitive in the Philadelphia suburbs.
The efforts to boost turnout have been extraordinary, so much so that in a weekend survey of battleground states by the Pew Research Center for the People & the Press, 6 in 10 voters said they had been personally contacted by one or both campaigns.
Among the 3 or 4 percent of voters still undecided, and the sliver of perhaps 6 percent more who tell pollsters that they are still persuadable, the choice may come down to issues as distinct as gay rights, abortion or stem-cell research.
Democrats said their lawyers have already worked to stop Republican suppression of Democratic votes in Michigan, Nevada and Florida.
"We have 10,000 lawyers that we have enlisted over the last months all across the country to guarantee . . . the right to vote is protected," Kerry told ABC News.
He added: "I'll do what's necessary to protect the constitutional right of Americans to vote."
The closer the vote in the Electoral College, the larger such disputes will become. The result could turn on a single state, even ones with small numbers of electoral votes such as New Hampshire with four and and New Mexico with five.
For all the visions of doom and gloom, however, some analysts are optimistic, describing the 2000 photo finish as a once-a-century fluke. "It could even be an early evening," said Karlyn Bowman, who studies polls for the American Enterprise Institute. "Some of the big, hotly contested states come in early."
The candidates themselves also struck optimistic notes.
Kerry told CBS: "I don't believe that we're going to have a protracted night. I think we're going to have a decision on Tuesday night, and America will move forward."
Over on NBC, Bush said: "I understand there's going to be close political contests, but we're one nation."