The Seattle Windshield Pitting Epidemic is a phenomenon which affected Bellingham, Seattle, and other communities of Washington state in 1954. It is considered an example of a mass delusion. It was characterized by widespread observation of previously unnoticed windshield holes, pits and dings, leading residents to believe that a common causative agent was at work. It was originally thought to be the work of vandals but the rate of pitting was so great that residents began to attribute it to everything from sand flea eggs to nuclear bomb testing.
Originating in Bellingham in March, police initially believed the work to be vandals using BB guns. However the windshield pitting was soon observed in the nearby towns of Sedro Woolley and Mount Vernon and by mid April, appeared to have spread to the town of Anacortes on Fidalgo Island.