Thirteen people were killed in nine separate traffic crashes in Michigan over the Labor Day holiday weekend, according to figures released by the Michigan State Police Wednesday. Of the thirteen victims, seven were not using seat belts. Alcohol was a factor in two of the nine fatal crashes. 2010's Labor Day holiday weekend is considered to be from 6 P.M. Friday, September 3rd, through midnight on Monday, September 6th. In 2009, sixteen people were killed on Michigan roads during the Labor Day weekend.