Creator/executive producer Matt Groening with his characters in February in Hollywood for "The Simpsons" 500th Episode Celebration. (Frederick M. Brown/GETTY IMAGES)

THIS IS A SPOILER ALERT, if you consider flashing a bright shiny fact into a quarter-century of darkness a “spoiler.”

The famed setting of Fox’s animation landmark “The Simpsons” has forever been the generically named “Springfield” — a fictional, nuke-loving town that may or may not have been named for a factual Springfield anywhere on the American map.

Now, thanks to “Simpsons” creator Matt Groening, let there be geographic light.

MATT GROENING shares a secret. (Valerie Macon/GETTY IMAGES)

“Springfield was named after Springfield, Oregon.,” says Groening, 58, who was born in Portland — so the reveal isn’t exactly out of left field.

“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,” Groening continues. “When I grew up, I realized it was just a fictitious name.

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“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.’
“ he says. “And they do.”

Some fans highly knowledgeable about both Oregon and “The Simpsons” have noted the show’s allusions to Portland over the years. Groening acknowledges: “I very early on named a lot of characters after streets in Portland. ... There’s Flanders, Kearney, Lovejoy. ... ”

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Asked why he’s never revealed the appellation inspiration of Springfield before, Groening replies:

“I don’t want to ruin it for people, you know? Whenever people say it’s Springfield, Ohio, or Springfield, Massachusetts, or Springfield, wherever, I always go, ‘Yup, that’s right.’ ”

Until now.

Today, there is no joy in other Springfields — mighty Oregon has lucked out.

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(courtesy of FOX's The Simpsons and TTCFFC / copyright 2009 )