Since then, the country has endured the 11 September 2001 terrorist attacks and fought two wars. But polls show the United States as split now as it was in the race between former Vice President Al Gore, a Democrat, and Republican George W. Bush.
Opinion surveys show only one or two percentage points separating Bush and Democratic challenger John Kerry, a longtime senator from Massachusetts.
Jennifer Duffy, who analyzes U.S. politics for the Cook Political Report, an independent newsletter, said it is again possible that no clear winner will emerge on election day.
"I think that we should all be prepared for a long night," Duffy said. "We should all be prepared for the possibility that we may not know election night -- that this race may go on for a few days."
Big issues such as the war in Iraq, homeland security, and health care have generated some of the highest interest in a presidential race in decades.
Voter registration levels have soared and political analysts predict a very high turnout.
Nearly two-thirds of the 50 states allow early voting. Media reports show more people have cast early ballots than ever before -- yet another sign of the hard-fought nature of the race, according to analyst Curtis Gans.
"With the conceivable exception of the [Democratic Party] primaries of 1968 and [President] Lyndon Johnson and the war in Vietnam, I have seen nothing in a lifetime that started in 1937 to rival the intensity of this election," Gans said.
Gans is director of the Committee for the Study of the American Electorate, a nonpartisan research institute that studies citizen engagement in politics. Presidential races tend to be referendums on the incumbent and Gans said that Bush is clearly a rallying point for both parties.
Polls show Bush's conservative base supports his leadership in the war on terror, tax cuts he has initiated, and his dedication to traditional values. At the same time, many Democrats scorn Bush, charging he is fiscally irresponsible, reckless in waging the Iraq war, and a divisive figure.
The format for electing the president, known as the Electoral College, will bring extra scrutiny on the polling process in a handful of key states. Under the system, candidates who win the vote in individual states gain the entire number of electors assigned to each state.
Overall, there are 538 members of the college and a candidate needs 270 electoral votes to win. The vote in 2000 came down to the contested result in Florida, where the U.S. Supreme Court ultimately ruled in Bush's favor, giving him the decisive number of electoral votes even though Gore had won the popular vote nationwide.
Amid concern about irregularities in Florida and other states, the U.S. Congress passed a law two years ago intended to bring more uniformity to locally run elections. The legislation for the first time provided federal funding to local authorities but the effort has been uneven, in part due to slow allocation of funds.
Statewide voter registration databases were supposed to be the centerpiece of reform but have only been completed in a minority of states. The lack of such databases above the local level could create problems, according to Doug Chapin, director of electionline.org, a non-advocacy website that is a leading source of news on election reform.
"Because these databases don't exist we don't have a tool to figure out if people are in the right place or if they really were registered," Chapin said. "We're still in the process of aggregating information from the local level to the state level as we have in the past."
The new federal law also allows voters to cast "provisional votes" when their registration is in doubt. There are expected to be hundreds of thousands of such ballots cast nationally but states have different deadlines for counting those votes.
Chapin said there could be a scenario similar to four years ago in Florida, not necessarily because of problems with the system but rather because of the number of monitors from both major parties looking for problems to occur.
"If we have the same kind of Florida-esque problem on election night, it will have more to do with how close the election is and where it's close than it is with any specific problems at the polls," Chapin said. "The threshold condition for an election challenge or an election controversy is that the election be close. So even if there are demonstrated problems in lots of states, if the election isn't close in any of those states the problems become more of a policy issue than a political issue."
Election day will also determine which party controls the two main legislative chambers. All 435 seats in the U.S. House of Representatives are being contested and there are races for one-third of the 100 seats in the U.S. Senate, the upper house of Congress.
Republicans are expected to maintain their control of the House of Representatives, where they have a 20-seat majority. Republicans also hold a 51-49 edge in the Senate and opinion polls give them a slight advantage.