In 1742, riots broke out in Philadelphia on Election Day over claims that German immigrants were being used to illegally increase vote totals. George Washington won a race for the Virginia House of Burgesses after buying gallons of liquor for voters; by contrast, James Madison refused to engage in this common practice and lost his election.

New York City was infamous for ballot stuffing throughout the 1800s. In 1844, for example, 135% of the eligible voters turned out to vote. William "Boss" Tweed's ability to steal elections in New York through the Tammany Hall machine was rivaled only by Mayor Richard J. Daley's Chicago operations in the latter half of the 20th century, although other cities had corrupt vote-stealing machines. Tammany Hall delivered fraudulent votes by buying them, through intimidation, by sending individuals from precinct to precinct to vote, and by using illegal aliens, fictitious voters and ineligible penitentiary inmates to cast ballots.

America is the most successful experiment in democracy that history has ever seen. Under the Constitution, Americans choose their leaders and legislative representatives, including federal, state, county and local governments. But when they vote Tuesday, will their votes be counted fairly? Or will ballots be canceled or diluted by fraudulent votes cast by the dead, noncitizens, fictitious voters, or individuals voting more than once?

We have allegations that almost a third of the 1.3 million registrations submitted by community organizer Acorn (Association of Community Organizations for Reform Now) are fraudulent. Not only do these bogus registrations slow down the ability of election officials to process the registrations of legitimate voters, but they severely limit the ability of election officials to verify new voters' registration information, because officials are overwhelmed by the sheer number of problem registrations.

This leads to serious questions about how many fraudulent registrations will not be caught by election officials. That raises the prospect that some ballots could be cast under successful fraudulent registrations, as has happened in real voter-fraud cases in the past. It will likely create chaos at the polls, where election officials will come under great pressure to not deny anyone's vote.

Vote-buying isn't just a remnant of our past. In 2003, the U.S. Department of Justice indicted seven individuals, who were ultimately convicted, for buying votes in Knott County, Ky. There are reports in this year's elections that votes were bought in some Alabama counties for cash and crack cocaine and that some voters appeared at the polls only to be told that absentee ballots had already been cast in their names.

Many of the techniques used throughout our history to cast fraudulent ballots, such as harvesting votes from felons who are ineligible or voters registered at false addresses, are still in use today.

Mayor Daley's vote-stealing machine was still working in 1982, six years after his death. A federal grand jury report detailed the massive voter fraud that occurred in the 1982 statewide election: The U.S. attorney estimated that 80,000 illegal aliens were registered to vote and 100,000 fraudulent votes were cast. The conspiracy came within 5,000 votes of stealing the governor's race.

The Tammany Hall tradition continued elsewhere. In 1984, a grand jury in Kings County (New York's borough of Brooklyn) reported on a voter-fraud conspiracy that had been simmering for 14 years. The New York Times headlined a story about the grand jury's report, "Boss Tweed Is Gone, But Not His Vote." People impersonating deceased voters, newly registered voters and fictitious voters whose names had been successfully registered without detection by election officials cast thousands of fraudulent votes in multiple elections.

In 1996, Loretta Sanchez won her congressional race in California against incumbent Bob Dornan by only 979 votes. An investigation found that more than 600 noncitizens voted, not quite enough to overturn the election. But that number of votes was more than the margin of victory in the 2000 presidential race in Florida, a state where the Department of Justice has convicted noncitizens for registering and voting.

More recently, the Milwaukee Police Department investigated the 2004 presidential election and found multiple problems with both registrations and voting. For example, 5,217 "students" were registered who listed their residence as a college dormitory that only houses 2,600 students; at least 220 ineligible felons voted; 370 registered addresses weren't legal residences in the city; some homeless individuals were registered in multiple locations; and residents of other states (including staffers for one of the major political parties) registered and voted in the election. John Kerry won Wisconsin by only 11,000 votes.

Think this won't happen again? Prosecutors in Ohio have already investigated 13 individuals from other states who registered in Ohio illegally; some listed a home in Columbus as their residence even though they don't live there. Student reporters, not local election officials, discovered the false registrations. Bogus ballots have already been cast (although since being caught, the out-of-staters are trying to pull their names from the rolls).

Unfortunately, some civil-rights organizations claim that prosecutions against voter fraud are racist and intended to suppress minority voters. Consider a federal investigation in the mid-1990s in Greene County, Ala., where 11 county residents, including several local officials, were convicted in voter-fraud cases.

Greene County is more than 80% black, so it should be no surprise that all of the defendants were black, as were candidates whose elections were stolen. Even so, the Southern Christian Leadership Conference (SCLC) said the investigation and prosecution amounted to "Gestapo tactics," and said it would have a chilling effect on voter turnout. But turnout went up in the county after the convictions as local citizens regained confidence that their vote would really count.

While such criminal investigations are laudable, they are rare. Voter-fraud cases are a low priority with most prosecutors and not worth the political cost, particularly the probability of being called a racist. Most election fraud in this country is never investigated or prosecuted.

Yet despite this history, partisan activists and some academics deny that voter fraud exists or that any steps need to be taken to protect the integrity of our election process. The Commission on Federal Election Reform, with former President Carter and Secretary of State James Baker as co-chairmen, profoundly disagreed. The commission found that the U.S. "electoral system cannot inspire public confidence if no safeguards exist to deter or detect fraud or to confirm the identity of voters."

The National Voter Registration Act, or "Motor Voter Act," of 1993 was supposed to make voting more accessible by making registration easier. But the legislation also complicated the process of dropping ineligible people from voter rolls, resulting in names remaining on the list for at least two additional federal election cycles. So the rolls are filled with voters who have died or moved. Some jurisdictions like Missouri and Indiana have more persons registered than their total adult population. Since people can vote in most states without proving their identity, such registrations are the gateway to voter fraud.

If a person can get on the list, he can vote in person or as an absentee without any scrutiny or consequences. And the ineligible voters on the list are there to be mined by anyone looking for extra votes. This is the root of two issues evident this year -- the push for voter identification at the polls and the focus on registration problems -- most notoriously, those of Acorn.

The U.S. is one of the few democracies in the world that doesn't require photo identification to vote. Photo ID protects not only against impersonation fraud, but it can prevent bogus votes from being cast based on fictitious voter registrations, by noncitizens, or by individuals who are registered in multiple states. This spring the Supreme Court upheld the constitutionality of Indiana's photo ID requirement, and courts in Georgia upheld its photo ID law. In all of these cases, despite claims that there are thousands of Americans who lack photo IDs, and after years of litigation, the plaintiffs were unable to produce a single individual -- not one -- who didn't have an ID and couldn't easily get one.

Numerous academic studies have shown that photo ID laws don't depress the turnout of voters, including minority voters. But many states still lack such a basic security requirement, and any state that passes such a law can expect extensive litigation against it.

The Help America Vote Act of 2002 required states to establish statewide voter-registration databases and to verify the accuracy of a registrant's information by comparing it to other state records, measures meant to minimize the likelihood of false registrations. Yet the Ohio secretary of state is refusing to forward information on a reported 200,000 mismatches to election officials who process voter-registration forms and make decisions on eligibility. (In mid-October the U.S. Supreme Court quashed a lawsuit against Ohio's secretary of state because a private party can't enforce the 2002 voting act, only the U.S. attorney general, who hasn't sued.)

Yes, some of these may be due to data problems. But only by investigating these mismatches can the state find fraudulent voter registrations. We need to replace our honor system with a system that verifies the authenticity of voter registrations and the ballots cast both on Election Day and through the absentee ballot process. Ensuring that only eligible people register and vote is not an effort to "suppress" certain groups from voting. It's a basic principle of ensuring integrity in our elections. Since we don't require identification (with some exceptions) or proof of citizenship when registering to vote, there is almost nothing to prevent noncitizens, fictitious individuals or real voters using false addresses from registering to vote. Because most states don't require photo ID to vote, we also can't detect these problems at the end of the election process when individuals are casting their ballots.

The right to vote in a free and fair election is the most basic civil right, on which depends all of the other rights of the American people. If an election is close, the possibility exists that the winner may be decided not by the American people, but by fraudulent votes cast by individuals exploiting the weaknesses in our current system.

Hans A. von Spakovsky is a visiting legal scholar at the Heritage Foundation and a former federal election commissioner.