The Windshield-Pitting Mystery Of 1954
In late March 1954, at the height of the Cold War, car owners in the Washington State town of Bellingham noticed strange pitting appearing on their car windscreens. Residents assumed it was vandalism but it soon spread to other towns nearby and became so prevalent and widespread to just be vandalism Soon the reports spread across the state and the police scrutinised the windscreens of 15,000 cars, finding over 3,000 affected vehicles. By mid-April weird and wonderful theories were being bandied about in the press - cosmic rays, radio transmitters even atmospheric coral from bomb tests carried on the wind.
Initial investigations by the police noticed strange particulate matter found in the glass and it only seemed to occur on the sloping front windscreen and not the vertical side windows or household windows. It also was more prevalent on older cars. State authorities contacted the Governor and President asking for a committee of scientists to investigate. A group formed from Washington State University examined cars in their car park and found the damage to be “overly emphasized,” and most likely “the result of normal driving conditions in which small objects strike the windshields of cars.”
The particulates were found to be coal dust from so many coal fires that had rained un-noticed in the polluted air. Though these didn't cause the pitting, car-owners simply started noticing their windscreen in the publicity and had not looked closely at them before to realise they simply get damaged with age and road gravel. Within a few weeks of it all blowing up, the hysteria died pretty quickly but it remains a classic example of mass-hysteria and investigators not looking for the simplest answers.