The answer to the question that has long puzzled Simpson's fans for years has finally been revealed. Every occasional viewer knows that Homer, Marge, Bart, Lisa and Maggie live in Springfield. But which Springfield has never been revealed...until now.

The show's creator, Matt Groening, told the Smithsonian Magazine that the town is based on Springfield, Oregon.

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 article, Groening also talks about the development of the show and talks about how it became such a big success.