The tale of disenfranchisement in this Southern town starts with a squirrel.

In 2014, the rodent chewed some wires at the historic Hancock County, Ga., courthouse in downtown Sparta, Ga., about 100 miles from Atlanta. A fire ensued, destroying the county’s entire voting roll – more than 1,100 names.

The Hancock Board of Elections immediately started rebuilding the rolls by urging voters to come in and register.

The next year, however, white county board members challenged 187 mostly black voters following complaints that they actually didn’t live in the precinct. Fifty-three people, nearly all African-Americans, were kicked off the rolls at a board meeting.

Marion Warren, a city election official, happened to be present. When his county counterparts heard a motion to begin challenging voters, Mr. Warren’s camera rolled.

His footage of a barely-attended hearing in a small American town led to a deeper investigation. Earlier this year, a settlement was reached between the county and the Lawyers' Committee for Civil Rights. Once it’s signed off on, it will make Hancock County the first jurisdiction to earn federal election oversight since the United States Supreme Court invalidated part of the Voting Rights Act in 2013.

The problem: The local board effectively – and illegally – disenfranchised voters, according to the settlement.

The US has for decades sought to understand the scope of voter fraud. The bottom line has been that while US voter rolls tend to be outdated – Pew has found that some 24 million registrations, or 1 in 8, may be inaccurate – evidence of actual in-person collusion and impersonation at the ballot box is exceedingly rare. One much-cited study found a total of 31 credible reports of voter fraud out of the 1 billion votes cast between 2000 and 2014.

Now, the Trump administration has launched its own investigation. At the end of June, the Election Integrity Commission sent a letter to all 50 states requesting their full voter-roll data, including the name, address, date of birth, party affiliation, last four Social Security numbers, and voting history back to 2006 of every voter in the state. Results are due July 14, but so far 44 states have said that they cannot comply with at least part of the request. The Department of Justice sent its own letter the same day, asking all 44 states covered by the National Voter Registration Act of 1993 for detailed information on how they purge their voter rolls.

“There are a lot of dimensions to the decision of an individual to vote and the administration of an election,” says Ken Mayer, a political scientist at the University of Wisconsin studying the voter patterns of the 2016 election. But from his research, some of which documents Americans forgoing the vote if the hurdle is unfair or too high, he is convinced that the “end game is to provide rationale for massive purges, and it’s not going to be Jennifer Andersons but Hector Gonzaleses who are going to face this.”

It’s a fraught-filled gambit, he argues: “There are huge constitutional consequences to making a mistake.”

The impact of such voter integrity crackdowns can be seen in places like Hancock County.

There, voter participation fell by 40 percent after local deputies were deployed to hand out summonses in person to the 187 people whose registrations were being challenged. (Often, such inquiries are mailed.) The Lawyers' Committee accused the county of voter intimidation and filed a lawsuit in 2015, after the mayoral election that saw Sparta get its first white mayor in four decades.

“If you look at what is happening now at the federal level, it is the exact same thing as what happened here in Hancock County,” says Mr. Warren.

Voter ID

Beneath two 27-inch Thunderbird monitors at the University of Wisconsin, Professor Mayer is pondering a question: Do strict voter ID requirements affect elections in real-time? Data from Mr. Trump’s critical win in Wisconsin last year already suggests they did. The question, he says, is by how much.

Surveys of past voters and analysis of provisional ballots – those cast by disputed voters – is yielding a trove of information about the extent to which stepped-up challenging, including involving sheriffs' deputies presenting summonses, leads especially low-income and minority voters to simply stop voting.

Georgia has become a major test case for a nation seeking to balance fraud concerns against the constitutional right to vote.

In 2005, with the help of Trump commission member Hans Von Spakovsky, Georgia pioneered a photo ID movement that is now status quo in more than 30 states. Former Secretary of State Karen Handel, who led that effort, was elected to the US House of Representatives last month. For two years in the Obama era, the state purged more names from its voter rolls than it registered new voters.

In March, US District Court Judge Timothy Batten Sr. found no problems with the state’s tactic of warning those who don’t regularly vote that they could be kicked off. “Maintenance of accurate voter registration rolls is a substantial governmental interest,” he wrote in his ruling.

But Emmet Bondurant, the lawyer who argued the case, has appealed the decision. He says not voting is just as much of a constitutional right as voting. “I expect a lot of people who have been purged in Georgia are people of color who were very enthused about Obama’s candidacy in 2008, voted for him, and then didn’t vote in subsequent elections, and were therefore purged,” he says.

The investigations going on from Hancock County to Washington, D.C., may help fill in the puzzle. In addition to the White House's voter commission and the Department of Justice's inquiry, the Supreme Court will hear several voting rights cases this fall, including an Ohio case that will test the extent to which states can purge voters from rolls.

In some cases, it has fallen on citizens like Warren in Sparta to hold officials accountable for unfairly or illegally denying people the franchise.

As the author of Cross Check – a system used by more than 30 states to check voter names against other states’ records – Kris Kobach, vice chair of the national commission and the Kansas secretary of State, has emerged as the nation’s foremost forensic fraud investigator.

But Mr. Kobach’s investigatory power has tested his own suspicions of “rampant” fraud. His office has prosecuted a total of nine cases of voter fraud since 2015. All but one were residents over 60 with properties in two states, who had gotten confused about where to vote. One was a non-citizen. Florida and Oregon recently dropped Cross Check, with Oregon officials complaining that the system was too error-prone.

'There is a reason I'm doing this'

But the White House commission has vowed to be thorough and fair in its investigation and recommendations. A letter sent to all 50 secretaries of State asks for voter data but also for input into how to prevent voter intimidation and disenfranchisement.

New Hampshire Secretary of State Bill Gardner, who has served in his capacity for more than four decades, joined the commission in May.

“There is a reason I’m doing this,” he told a local public radio station. “I care a lot about this. I’ve spent my whole life dealing with it, and it’s too bad that over half of the people in the country feel that there is vote fraud. Let’s find out why.”

The problem, voting rights experts say, is less gathering evidence than understanding what it means.

There’s little doubt that voter fraud and impersonation happens in the US, and has happened historically. But there is no evidence that it is widespread. Usually, the reasons are mundane mistakes. No elections in the modern era have been swayed by fraudulent in-person voting, according to research by political scientist Rick Hasen, a professor at the University of California, Irvine, and author of the Election Law Blog.

'If you really want to vote, you can find a way'

That building tension between voter integrity and suspicions of fraud is evident here in Sparta. Yes, some voters kicked off the rolls had moved, primarily for work and school. But they still considered Sparta home, which is why they had not registered to vote anywhere else.

Hancock County election supervisor John Reid says that the voter roll purge “probably did turn some people off because it was intimidating.” But to him, the voting right is also in part a matter of personal responsibility – something worth fighting for. “If you really want to vote, you can find a way,” says Mr. Reid, an African-American.

For many African-Americans, however, such hoop-jumping has a familiar feel. Historically, from Reconstruction to the civil rights era, gains in voting rights have been followed by retrenchment, often at the hands of white officials seeking to preserve a demographic and political status quo against the country's growing racial and political diversity. Since the 2013 Supreme Court Shelby v. Holder decision, which invalidated part of the Voting Rights Act, formerly DoJ-supervised states such as Texas, Alabama, and North Carolina have invoked stricter voting rules that courts have found disproportionately affect young people and low-income minorities, who tend to vote Democrat.

Up in Wisconsin, Mayer's research may help resolve some of the tension. He says county clerks are awaiting his fact-finding report on the 2016 election to help them encourage, not discourage, people to vote.