Michigan's historical markers are vulnerable to metal thieves.
The state Historic Preservation Office lists 40 markers around Michigan, including 19 in Detroit, which have been stolen or misplaced over the years.
The cast aluminum markers weigh enough to fetch up to $70 at a scrap yard. Historians say it's time to replace the signs with something cheaper.
Two years ago, the state beefed up penalties for stealing or damaging the popular signs. But state officials say no one has ever been prosecuted under the law.