If the Janus decision was a car crash for public-sector unions, on first inspection it looks like it resulted in a minor dent, at least locally.

But it might have left structural damage.

In Minnesota, nearly all the roughly 196,000 public sector employees who are covered by a union contract were members of their respective unions in 2017, according to data compiled by researchers Barry Hirsch of Georgia State University and David Macpherson of Trinity University.

So when the Supreme Court decision that prevents public sector unions from collecting "fair share fees" from nonmembers took effect in June, just 2,000 Minnesota employees saw their contract-bargaining contributions end.

That's not an easy reduction to cope with, but in many states the gap between union membership and coverage is much wider. What labor organizers are bracing for next, however, is more members opting out.

"There are folks out there who are actively working to communicate to union members: 'You get rid of union membership it's a pay raise,'" said Duluth Federation of Teachers president Bernie Burnham. "But we work hard to take care of our folks."

One study says public-sector union membership in Minnesota could drop from 54 to 46 percent, which would wipe out about 16,000 dues-paying members. That in turn could scramble the budgets and organizing abilities of public-sector unions, with some advocates warning of even more dire outcomes.

"The organizational, legal and political response to Janus will be critical to the long-run survival of the U.S. labor movement and the American middle class," write researchers Frank Manzo with the Illinois Economic Policy Institute and Robert Bruno with the University of Illinois.

Unions representing government employees, teachers, firefighters and other public servants got ahead of the ruling by getting members to reaffirm their commitments in recent years.

"We worked really hard in past few years to re-engage our folks about the value of belonging," Burnham said. "I'm feeling really good."

Some former fee-payers have approached their union and asked to join, said Tim Henderson, associate director with the American Federation of State, County and Municipal Employees Minnesota Council 5. Others have not.

"We call them free-loaders," he said. "We have a conversation with them and they still decide to opt out."

In Wisconsin, public sector unions have been prohibited from collecting fair-share fees since 2015 and have faced limited collective bargaining since 2011. So while that state won't see an effect from the Janus ruling, it could be indicative of what's to come: The gap between union members and those covered by a union has grown much larger than it is in Minnesota.

For now, the North Star State is tied with Connecticut in having the smallest gap between those public-sector employees covered by collective bargaining and those who are union members.

At Labor Day picnics around the state Monday, the message will no doubt be to keep it that way.

"Our message is clear: If you want a contract then you need to be a member," Henderson said. "It's a committee of the willing."