From Yahoo! Answers.
Haddonfield, New Jersey, is the home of "Halloween" co-screenwriter Debra Hill. John Carpenter, screenwriter and director, was raised in Bowling Green, Kentucky, and there is a small town of Smith's Grove 15 miles from Bowling Green.
The movie, however, despite its fall setting, was actually filmed in southern California in the spring.
The original movie referred to Haddonfield as just being somewhere in Central Illinois (which is around Springfield).
The 6th Halloween movie, "Halloween: The Curse of Michael Myers" was directed by Chicago native John Chappelle who chose to have Haddonfield located in Livingston County, about 70 miles south of Chicago. The movie featured a map of the area in the deserted bus station before Michael broke in and that is where I saw Dwight and Pontiac.
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