Stephen King's IT was inspired by a walk that he took through Boulder. This is how the creepiest clown novel and movies ever got started.

If you haven't seen IT, be prepared to get scared within the first five minutes of the movie alone. Stephen King's inspiration for this terrifying movie came from a walk in place a little too close to home --- Boulder. While King and his family lived in Boulder, one day the transmission of their AMC Matador dropped, literally, it fell onto Pearl Street. Instead of getting a cab to the AMC dealership, King decided to walk. According to Stephen King's official website:

The AMC dealership was in an industrial park set off by itself on a patch of otherwise deserted land a mile from the strip of fast-food joints and gas stations that mark the eastern edge of Boulder. A narrow unlit road led to this outpost. By the time I got to the road it was twilight--in the mountains the end of day comes in a hurry--and I was aware of how alone I was.

 

This is where the inspiration for the movie comes from, as King crosses the bridge, he thinks of the trolls that could be underneath it. King remembers this idea because "a good idea is like a yo-yo--it may go to the end of its string, but it doesn't die there; it only sleeps. Eventually, it rolls back up into your palm." He continues to think of this idea, of trolls under bridges, of tunnels and sewers under cities. King decided sewers would be "a good place for a troll!"

Time continues to pass as King keeps rethinking of this idea, he thinks of spending time as a child in a library in Stratford, Connecticut. There was a corridor connecting the adult and children's sections, much like a bridge, much like the bridge in Boulder. King continued to think of this idea and...

...how such a story might be cast; how it might be possible to create a ricochet effect, interweaving the stories of children and the adults they become. Sometime in the summer of 1981 I realized that I had to write about the troll under the bridge or leave him--IT--forever.

I guess that Stephen King decided to write about it, the novel IT came out in September 1986, the movie in November 1990 and the most recent version came out September 8 of this year. Although the troll is gone, at one point King said: "what scares children more than anything else in the world?" I think you know the answer to that. Good luck sleeping, thinking about clowns and being around drains and sewers after you watch this IT. Oh yeah and IT is only part one, so expect more creepy clowns to head your way.

Source: 99.9 The Point and StephenKing.com