The Simpsons has aired more than 500 episodes and been the subject of numerous analytic and academic examinations, so it seems there can be little mystery remaining regarding the family at the center of Fox’s animated series that is the longest-running situation comedy in American TV history. But Simpsons creator Matt Groening did solve one of the few remaining mysteries in an interview with Smithsonian magazine: the native of Portland, Ore., revealed that the fictitious Springfield where Homer, Marge, Bart, Lisa and Maggie Simpson live is in fact based on a town not far from where he grew up.

“Springfield was named after Springfield, Oregon,” Groening told Smithsonian. “The only reason is that when I was a kid, the TV show Father Knows Best took place in the town of Springfield, and I was thrilled because I imagined that it was the town next to Portland, my hometown. When I grew up, I realized it was just a fictitious name. I also figured out that Springfield was one of the most common names for a city in the U.S. In anticipation of the success of the show, I thought, ‘This will be cool; everyone will think it’s their Springfield.’ And they do.”

In the 2007 feature film The Simpsons Movie, Ned Flanders takes Bart to a hill top and tells him to look around at the four states that border Springfield: Ohio, Nevada, Maine and Kentucky.

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