The letter arrived at the Guetschow house before Election Day.

It included the names and addresses of three of their neighbors in Minnetonka, and a chart showing whether they had voted in 2010, 2012 and 2014.

"We're sending this mailing to you and your neighbors to publicize who does and does not vote," the letter said. "We will be reviewing these records after the election to determine whether or not you joined your neighbors in voting."

The signature: "Election Day Coordinator." It had no return address or letterhead.

Jan Guetschow said that sounded sinister, like Big Brother. "Voting is supposed to be private. We each do our own thing."

Your choice in the ballot box is private. The names and addresses of registered voters, and whether they voted in a given election, are public information under state law. And the information is pretty easy to access, it turns out.

The Minnesota Secretary of State must provide it to anyone who asks, although the information cannot be used for anything but election and political purposes.

Letters of this ilk have become common enough in recent election cycles to gain a name: voter shaming. If you don't vote, your neighbors will know, say the letters, which have been used by both major parties.

"While they 'appear' to be official government communication, they are not, which we always explain if asked," Ryan Furlong, a spokesman for Secretary of State Steve Simon, said via e-mail. "You can check with the political organizations who sent them — but I believe that type of letter has been sent for a few election cycles now."

Voter shaming letters are often sent by organizations with nondescript names (the Kansas State Voter Report) that take some detective work to trace back to their true identity, usually a partisan organization.

The Guetschows received another, more modest voting appeal letter that showed Jan's husband's turnout in recent elections, vs. the state as a whole. That was sent by America Votes, a Washington, D.C., group whose website describes itself as "the coordination hub of the progressive community."

The letters can sound creepy. But they work, or so concluded a 2008 study by political scientists at Yale University and the University of Northern Iowa.

They mailed get-out-the-vote letters to 80,000 households in Michigan ahead of the 2006 primary, and the highest turnout occurred among those who received a voter shaming letter.

Since then, they have shown up during campaigns in Kansas, Florida and other states. Texas Republican Sen. Ted Cruz got harshly criticized in January after his campaign sent letters to GOP primary voters in Iowa's presidential caucus.

The letters screamed "Voting violation" and alerted residents that voting histories were public records, and that they may be contacted again after the caucus, according to a CNN report.

The anonymous letter to the Guetschows is "the least transparent we've seen," said Jordan Libowitz, communications director for Citizens for Responsibility and Ethics in Washington. The nonpartisan advocacy group has studied voter shaming letters.

"Where others list a mystery organization we were able to trace to a law office in New York, this one has nothing at all," Libowitz said. "There's no one to complain to when you have no idea who sent it."

There is not likely to be much political will to restrict access to voter information, given how much the political parties depend on registration data and voting history to target get-out-the-vote efforts.

Jan Guetschow, who's 76 and works part-time at a fitness center, said she and her husband don't need any external pressure to do their civic duty on Election Day.

"If I knew who it was," she said, referring to the sender of the mystery letter, "I would have voted against them."

Contact James Eli Shiffer at james.shiffer@startribune.com or 612-673-4116.