While at least five residents reported getting the fliers, no one was seen distributing them, the Chicago Tribune reported.
There have been several incidents in the past two years of KKK material turning up in Tinley Park. But Police Chief Steve Neubauer said no laws appear to have been broken.
The first incident occurred in January 2012 when a woman reported finding a leaflet left on her car in the parking lot at a commuter rail station. The leaflet contained the warning: "If you have Caucasian children, they could be in the minority."
More than 90 percent of Tinley Park's 56,000 residents are white, according to Wikipedia.
The only violent incident occurred in May 2012 when 18 masked men showed up at the Ashford House Restaurant, apparently responding to a tip that white supremacists had gathered there.
The alleged supremacists were beaten by six men believed members of the Hoosier Anti-Racist Movement who were charged with armed violence. Five have pleaded guilty and been sentenced to as long as six years in prison.