An annual report by the Governor's Highway Safety Association finds that motorcyclist traffic fatalities rose 10% across the nation between 2014 and 2015, and the increase was substantially greater in Michigan.
Fatal motorcycle accidents rose 23% in Michigan.
Co-author Richard Retting says there could be many factors responsible, including better weather in 2015, along with more vehicles of all kinds on the highways.
But he says Michigan's repeal of its mandatory motorcycle helmet law in 2012 very likely was a factor, too.