Twitter has come under fire for fact-checking President Trump's tweets about the potential for fraud in mail-in voting, but it seems as though Twitter itself needs a fact check: There is a long, troubling history of fraud committed through mail-in ballots.

In the 1982 Illinois gubernatorial election, more than 100,000 votes were fraudulently cast in Chicago. The Justice Department found that Democratic Party officials there had set up an extensive vote fraud ring that very nearly stole the governorship from Republican Jim Thompson, who won re-election over Adlai Stevenson III by just 5,074 votes out of 3.67 million cast.

Following an extensive federal investigation, a total of 63 people were convicted on vote fraud charges. Prosecutors found that they had bought votes, registered illegal immigrants and imaginary voters, and even had voting precinct captains physically change their vote counts. But by far their most common trick was casting fraudulent absentee ballots. The corrupt precinct captains who were in on the fraud had their workers "encourage voters to apply for absentee ballots whether or not they had a valid reason to do so and to turn the blank ballots over" to the election workers, who would then vote for them.

The investigation found that "although the [vote] canvass disclosed that a number of persons who were registered to vote in the precinct had died, moved away, or for some other reason had become ineligible to vote, these persons were not struck from the list of eligible voters. Finally on election day the defendants, either personally or by acting through others, caused numerous false ballots to be cast for the straight Democratic ticket."

The conspirators preyed on the elderly and infirm, because they "would be the most unlikely to challenge the theft of their franchise."

12 years later, in Greene County, Alabama, eleven people were convicted of widespread vote fraud through the use of phony absentee ballots.

"The defendants included Greene County commissioners, officials, and employees; a racing commissioner; a member of the board of education; a Eutaw city councilman; and other community leaders," a White House report concluded. "The conspiracy included using an assembly line to mass produce forged absentee ballots meant to swing elections in favor of preferred candidates."

That "assembly line" involved the conspirators filling out ballots that they had fraudulently mailed to them and then sending them back on Election Day. Some of those involved in the scheme even went so far as to steal ballots out of people's mailboxes!

That same year, the mayor's race in Hialeah, Florida had to be re-run because "so many forged absentee ballots were cast...that the results were void." Incumbent Mayor Raul Martinez (a convicted felon who was allowed to run while awaiting sentencing on corruption charges) had his win reversed. The Los Angeles Times reported at the time that "Circuit Judge Sidney Shapiro found that the mayor’s 2-to-1 advantage in absentee ballots may have come from the efforts of 'overzealous' campaign workers at a retirement home, where many voters suffer from schizophrenia and drug addiction."

In other words, members of the mayor's campaign simply filled out ballots for those residents and mailed them back in.

Three years later, the 1997 Miami mayoral election also had to be re-run after 36 people were arrested for cheating the absentee ballot process. As the Miami Herald noted, "numerous absentee ballots were cast in the primary by people who live outside of the City of Miami. Some voters were unaware they had voted at all. One ballot was cast by Manuel Yip, who has been dead for four years."

When the fraud was discovered and the election was held again, a different candidate won.

In 2003, a member of East Chicago Mayor Robert Pastrick's campaign was found guilty of casting fraudulent ballots by promising jobs to people in exchange for letting him vote for them in the primary. Because of this widespread fraud, the primary was re-run and Pastrick lost.

Five years later, community activist group ACORN engaged in what Washington's Secretary of State called "the worst case of voter registration fraud in the history of the state" by submitting nearly 2,000 fake voter registration forms. According to CNN, the group "took addresses from homeless shelters, used fake birthdays and Social Security numbers and took names from baby books to create voters out of thin air."

Clifton Mitchell, the ringleader of the scheme, spent three months in prison, and four of his co-conspirators were sentenced to jail time. ACORN itself was fined $25,000. The group was under investigation for fraud in 10 different states for its activities ahead of the 2008 presidential election.

The following year, The Wall Street Journal reported:

Nevada officials charged ACORN, its regional director and its Las Vegas field director with submitting thousands of fraudulent voter registration forms last year. Larry Lomax, the registrar of voters in Las Vegas, says he believes 48% of ACORN's forms "are clearly fraudulent." Prosecutors in Pittsburgh, Pa., also charged seven Acorn employees with filing hundreds of fraudulent voter registrations before last year's general election.

In 2012, Martin, Kentucky Mayor Ruth Thomasine Robinson ran a mail-in ballot scheme that preyed on people who lived in properties she either owned or supervised. The FBI said in a press release:

According to evidence at the trial, Thomasine Robinson and her co-conspirators intimidated poor and disabled citizens in order to gain their votes during Robinson’s 2012 campaign for re-election. For instance, members of the conspiracy directed residents of public housing to vote by absentee ballot under the supervision of Thomasine Robinson or another member of the conspiracy. The conspirators also targeted residents of private housing owned and leased by Thomasine Robinson.

Trial testimony established that the conspirators completed absentee ballots, marking their choice of candidates, and instructing the voters to sign the pre-marked ballots. Voters who complied by voting for Thomasine Robinson received promises of better living arrangements and other considerations. Voters who did not comply faced eviction or the loss of priority for public housing. In addition, the evidence established that the defendants offered to pay several voters to vote for Thomasine Robinson.

She was convicted on vote fraud and civil rights violation charges and sentenced to 90 months in federal prison.

In 2017, investigators found widespread mail-in fraud in Dallas City Council elections. Dallas Magazine explained the "harvesting operation" in a lengthy profile of the man who discovered it:

It starts with a knock. Someone in your family opens the door, because you’re old, most likely over 80, certainly poor, possibly infirm, probably a minority. You see a familiar face. She is a community organizer, young, passionate. She has come by often, campaigning for Obama or Wendy Davis. Today she comes bearing a fruit basket, because she wants to help. She’s also kind enough to carry in your mail.

It just so happens that today’s mail brings a large envelope. The envelope contains a letter from the Secretary of State, who thanks you for doing your civic duty. There are pages of instructions in English and Spanish. There is a mail-in ballot for early voting. There is a carrier envelope that must be signed and used to deliver the ballot. The nice woman with the fruit asks if you’d like some help filling out your ballot. Of course you would. It’s all very confusing. She asks you to sign on the envelope and says she’ll take care of the rest.

That’s one scenario. The details can change. The harvesters who show up just as your ballot is delivered, maybe they have to ask you if you’ve already brought your ballot inside. Maybe they find the package in the mailbox, put it on a clipboard, and ask you to sign your name to the carrier envelope for some bogus reason. Maybe you never vote, so these harvesters just take your ballot out of the mailbox for themselves—and you never miss it.

Why are these big envelopes being sent to many people who didn’t even request a mail-in ballot? Because before these ballots were harvested, these precincts were “seeded.” Large batches of applications for ballots, stuffed in manila envelopes, had arrived at the county elections office, each request with a name from voter lists that had also been requested from said office. That elections office alerted harvesters to when the precincts would receive their ballots by mail, so the nice woman with the fruit would know when to have her basket ready.

This is, broadly speaking, how the mail-in ballot game works across Texas and how it has worked in Dallas County for decades.

The following year, in what is perhaps the best known vote fraud case since the 1982 Chicago election, a Congressional race in North Carolina was upended over massive mail-in vote fraud. After Republican Mark Harris beat Democrat Dan McCready by just 905 votes, it became clear that a Harris operative named L. McCrae Dowless, Jr. was running a fraud scheme. He requested more than 1,200 absentee ballots on behalf of unsuspecting voters. When the ballots arrived at their homes, Dowless picked them up and had assistants fill them out.

Dowless and four people who worked for him were criminally charged and the race was re-run. The Republican Party rescinded its support for Harris and he announced that he wouldn't run. Instead, Republican Dan Bishop beat McCready to win the seat.

The next year, Sherikia Hawkins, the Democratic City Clerk of Smithfield, Michigan, was charged with fraud for altering 193 ballots that were mailed to her office ahead of the 2018 midterm elections.

As if nearly 40 years of continual fraud associated with mail-in balloting weren't enough, on the exact same day that Twitter fact-checked President Trump's claims, a mail carrier in West Virginia was charged with attempted vote fraud.

Thomas Cooper allegedly changed party affiliations of eight voters on their requests for mail-in ballots. According to an affidavit, he admitted to the crime but claimed that he did it "as a joke" and was "just being silly."

Such widespread vote fraud, of course, is no joke--especially when it spans four decades. And mail-in balloting makes fraud easier. If Twitter is looking for a fact-check, it might ask former President Jimmy Carter and Secretary of State James Baker, who co-chaired the 2005 Commission on Federal Election Reform. One of its primary conclusions was definitive: "Absentee ballots remain the largest source of potential voter fraud."