When it comes to election fraud, the "voting twice by dressing up with a different hat" tactic that President Trump talks about almost never happens.
What actually does happen, as allegedly illustrated in the race for North Carolina's 9th Congressional District, is vote-by-mail fraud.
"The consensus, among people who study fraud carefully, is that voting by mail is a much more fertile area for fraud than voting in person," said Charles Stewart, who studies election technology and administration at Massachusetts Institute of Technology.
Still, voting by mail is on the rise. The numbers aren't finalized for 2018 yet, but in the 2016 presidential election, the percentage of people who voted by mail had more than doubled compared to two decades prior.
Supporters say it increases turnout, because it is significantly more convenient for most voters. With voting by mail, there are none of the long lines that were seen across the country this year, as turnout for a midterm reached 50-year highs.
Voters also get weeks to mull over and fill out a ballot in the comfort of their own home, with research resources handy.
All of this sets up a quintessential question about American elections: how much security are the American people willing to sacrifice to make voting convenient and accessible for everyone?
North Carolina isn't alone
Similar to in-person fraud, the amount of vote-by-mail fraud is still minuscule in the context of the hundreds of millions of ballots that have been cast in the past decade.
"All sorts of election fraud are very rare in the United States," Stewart said. "That's always the caveat you have to give."
But it happens. A Washington Post article from 2012 laid out six cases where local races were affected by vote-purchasing and absentee-ballot requests.
"The first votes I ever bought, I paid a half a pint or a pint of liquor, whatever it was, for it," said Kenneth Day, in a 2010 trial in eastern Kentucky, according to The Post. "And then, as time went on, $5 a vote, $10 a vote. I have paid as high as $800 a vote."
In North Carolina, the State Board of Elections is investigating voting irregularities in the 9th Congressional District, centered on the actions of a man named Leslie McCrae Dowless.
Multiple people have come forward to say that Dowless paid them to collect absentee ballots, which is illegal in North Carolina. A number of Bladen County voters have also come forward to say people collected their ballots, sometimes before they were sealed or completed.
Dowless declined to comment when he was reached by NPR on Thursday.
Post-election data showed Republican Mark Harris winning an abnormal share of the absentee ballots in Bladen County compared to the amount of registered Republicans who turned in absentee ballots in the county. There were also an abnormally high number of unreturned ballots in a neighboring county.
Harris currently leads Democrat Dan McCready by 905 votes in the unofficial vote tally, but the state board is looking into whether the count is tainted by fraud, and whether a new election needs to be called. The board also officially announced Dowless as a person of interest on Friday.
Could mail backlash be coming?
Washington is one of three states that is an all-mail state, which means every registered voter in the state receives a ballot in the mail automatically. They can mail it in or drop it off at one of hundreds of drop-off locations around the state.
Whereas North Carolina has a law on the books specifically aimed at stopping the kind of "ballot harvesting" operation Dowless is accused of running, as only a voter or their close relative is allowed to turn in a ballot in the state, Washington has no such law on the books, said Lori Augino, director of elections for the office of the Washington Secretary of State.
Augino noted, however, that she is not worried about a similar operation happening in her state. Because the state pays for postage for every ballot it sends, voters should have virtually no incentive to hand over their absentee ballots to someone volunteering to turn them in.
"Every mailbox becomes a ballot drop box that can be used free of charge for a voter," Augino said, "so there aren't a lot of reasons a voter would need to rely on someone else to return their ballot."
Colorado is also a vote by mail state, and Judd Choate, the elections division director for the Colorado Department of State, said a certain amount of responsibility for ballot safety in vote-by-mail systems relies on the voters. He said if someone gives up their ballot without signing or filling it out, "that's an irresponsible voter."
"That's the same thing as giving someone a blank check and signing it," Choate said. "You should have no faith that person is going to do what you intended with that ballot."
Choate added that people with bad intentions can defraud any system of voting if the right policies aren't policed or enforced, and if voters aren't educated.
Tammy Patrick, a senior adviser for elections at the Democracy Fund and a former election official in Arizona, said that in every instance, as states make voting by mail easier, more and more voters begin using it. In 2016, six states that were not all-mail states, saw more than 50 percent of all ballots cast through the mail.
Patrick, along with other supporters of vote-by-mail are worried that the case in North Carolina will be used as an argument to limit the practice, despite its benefits — and voters' desire for it.
"I think it's something we need to resist as a reaction," Patrick said. "If and when a bank gets robbed or a car gets stolen, we don't stop using banks or cars. We enforce the laws we have in place."