[Robert Dallek is a presidential historian, and recently authored"An Unfinished Life: John F. Kennedy, 1917-1963" (2003, Little Brown).]

In 1968, after rioting at the Democratic convention in Chicago underscored the bitter divide in the United States over the Vietnam War, a French travel agency urged its customers to"see America while it lasts."

Today's antagonism rivals what happened in 1968. Although we've not seen massive demonstrations or violence in the streets as we did that year, the anger over the 2000 campaign and over issues such as stem cell research, civil liberties and the Iraq war is as intense as anything we've heard in the last 100 years. Regardless of who wins today's election, the deep division in the country seems likely to survive and fester into the next administration.

But although this is clearly a bitter and partisan moment in American history, it is important to remember that we have been here before. This is not the first time the U.S. has been at war with itself. Even if we do face an electoral mess on Wednesday, or even a constitutional crisis, we should recall some of our earlier efforts -- all successful -- to subordinate political antagonisms to a national consensus.

At the turn of the 19th century, for instance, during an unusually ugly campaign about the nation's course at home and abroad, Thomas Jefferson was described as the antichrist who would cause blood to run in the streets. Still, when he was finally selected in 1801 as the new president by the House of Representatives over Aaron Burr, he chose not to continue the bitterness."We are all Federalists. We are all Republicans," he said.

In 1864, during the Civil War, which was the greatest threat in the country's history to its survival as one nation, Abraham Lincoln promised"malice toward none; charity for all."

In 1901, after William McKinley's assassination in a nation struggling with class warfare produced by the Industrial Revolution, Theodore Roosevelt rallied the country with promises of a"Square Deal" -- a government serving the general interest rather than any special interest.

In October 1968, after Democratic candidate Hubert Humphrey learned that his GOP rival, Richard Nixon, (in violation of the Logan Act) had discouraged the South Vietnamese government from participating in the Paris peace talks -- a potential October surprise that could have transformed the election -- Humphrey chose not to reveal it. The journalist Theodore White called that decision"an uncommon act of political decency."

Should today's election turn out to be as closely divided as the 2000 election, let us hope that both sides will put the national well-being above self-serving purposes. Conceding the presidency after so long and arduous a campaign will not be easy. But to have teams of lawyers again battling over hanging chads and voter intimidation does not seem like a prescription for renewed confidence in our electoral process. No one wants to see Americans cheated out of their right to vote or any candidate denied the support legitimate voters wish to give him. But a bitter-end fight to win the presidency will serve neither the country's political stability nor the candidates' historical reputations. Sensible restraint should be the motto of both sides in any postelection disputes.

The fact is, the country will come together again. Seemingly unbridgeable differences in the past have found solutions. Majority doubts about legitimizing labor unions, abolishing Southern segregation or having a Catholic as president were decisively ended by the experience of the last 70 years. Likewise, fears that a federal pension system and national health insurance for seniors would undermine free enterprise have also proved false. Contemporary antagonisms over stem cell research, abortion rights, environmental protections and gun control -- and even issues as volatile as Iraq -- will at some point lose their urgency as new issues rise to the fore.

Those who see politics as a vehicle for realizing personal ambitions should remember John F. Kennedy's enduringly wise advice to the nation:"Ask not what your country can do for you -- ask what you can do for your country." And in this case, it is to find a way to get along.