I've heard it so many times that I considered it a fact.
All across the United States, listeners reacted. Thousands of people called radio stations, police and newspapers. Many in the New England area loaded up their cars and fled their homes. In other areas, people went to churches to pray. People improvised gas masks. Miscarriages and early births were reported. Deaths, too, were reported but never confirmed. Many people were hysterical. They thought the end was near.
According to HowStuffWorks:
By the middle of the hour-long program, hundreds of thousands of Americans had bought the hoax, believing that martians had actually landed on Earth.
But here it says:
[a new book offers] compelling evidence that the panic and mass hysteria so readily associated with The War of The Worlds program did not occur on anything approaching nationwide dimension.
Author W. Jospeh Campbell is cited:
Like many media-driven myths, claims about the 1938 radio dramatization seemed too good, too delicious, to be true. Those claims, essentially, were that Americans by the tens of thousands—even the hundreds of thousands—were pitched into panic and mass hysteria by listening to the radio show.
The anecdotal news reports simply did not rise to the level of nationwide panic and mass hysteria. Had there been widespread panic and mass hysteria that night, newspapers for days and even weeks afterward would have been expected to have published details about the upheaval and its repercussions. But as it was, newspapers dropped the story after only a day or two.
It’s true that calls surged in many parts of the country, especially in metropolitan New York and New Jersey, but many of the callers were seeking confirmation or clarification, which is an altogether rational response.
... newspapers seized the occasion to bash radio in the aftermath of the show. This unrelievedly negative commentary reinforced the notion that The War of the Worlds program had sown panic and mass hysteria among Americans.
Here is a Youtube clip in which W. Joseph Campbell talks about the media myth.
Is it indeed just a myth that Orson Welles' radio broadcast caused a widespread panic?
What are the most realistc estimates of how many people actually paniced?