If this year’s elections stick to historical trends, Maine next month is likely to post one of the highest levels of voter participation in the nation.

The last time Maine elected a governor, its voter turnout level — 55.2 percent, according to the United States Election Project — was behind only Minnesota’s. In 2008, Maine — with 71.8 percent participation — trailed only Minnesota, New Hampshire and Wisconsin. Four years later, Maine’s turnout slipped to 69.2 percent, but the Pine Tree State still placed sixth for turnout.

Between 2008 and 2012, turnout in Kansas and Tennessee also slipped — but by greater amounts than it did in Maine and in the U.S. overall. The implementation of photo ID requirements for voters explains the decrease in those states above and beyond the slides seen everywhere else, according to the U.S. Government Accountability Office.

Photo ID requirements for voters took effect in both those states in time for the 2012 election. Those who couldn’t present a valid photo ID at the polls could cast provisional ballots that were counted only if voters presented valid photo IDs within a specified period after the election. (In Kansas, 37 percent of provisional ballots cast for ID reasons were ultimately counted, according to the GAO; in Tennessee, 26 percent were counted.)

At the request of five senators — four Democrats and independent Sen. Bernie Sanders of Vermont — the GAO set out to assess the impact on turnout of voter photo ID requirements. The agency settled on comparing Kansas and Tennessee with Alabama, Arkansas, Delaware and Maine in an effort to isolate the impact of changes in voter ID requirements from all other factors that could affect voter turnout.

The finding? That the enhanced ID requirements in Kansas and Tennessee were responsible for a 2- to 3-percentage-point drop in voter turnout from four years earlier.

Kansas’ turnout dropped 5.4 percentage points between 2008 and 2012 — to 58.1 percent in 2012. Tennessee’s dropped 4.8 percentage points, to 52.6 percent in 2012. The implementation of photo ID requirements, then, was responsible for about half of the drop. Maine’s turnout, by comparison, slid 2.6 percentage points over the same period; the nation’s dropped 3.5 points.

The GAO — which stressed that its findings can’t be applied beyond Kansas and Tennessee — also found that the turnout suppression was most pronounced among young, recently registered and African-American voters.

Strict photo ID requirements will be in place for voters this year in seven states, according to the National Conference of State Legislatures. Fortunately, Maine has resisted multiple legislative proposals that would have instituted photo ID requirements at the polls. And Maine voters in 2011 turned back legislation that would have repealed the state’s long-time tradition of allowing voters to register on Election Day.

The fact that Maine is among the highest-turnout states in the country and that it has erected few barriers to voting among eligible voters is no coincidence. And there’s no reason that should change.

Proponents of photo ID requirements for voters have said they’re trying to crack down on voter fraud. In fact, the Kansas Secretary of State’s office suggested to the GAO that its depressed turnout was in part due to fewer fraudulent votes being cast. But repeated analyses in multiple states — including Maine — have turned up few if any documented cases of voter fraud. So photo ID requirements are a feel-good — if cumbersome — solution to something that hasn’t proven to be a problem.

In the process of solving a problem that arguably doesn’t exist, photo ID requirements can keep a significant number of voters away from the polls — as evidenced in Kansas and Tennessee. A review of relevant research on voter ID by the GAO found 84 to 95 percent of registered voters had the required photo IDs. The Washington Post calculated that the effect of Kansas’ and Tennessee’s requirements was 122,000 fewer votes cast.

Those are more than 100,000 people who would have exercised their right to have a say but couldn’t because of a photo ID requirement. In our estimation, that’s a requirement that creates, rather than solves, a problem. Maine voters should be thankful no such requirement exists here.