Matt Groening -- The Simpsons ... Are Wildcats???

Springfield is NOT in Oregon ... or Illinois ... or Delaware ... or Ohio, Nevada or Maine ... so says creator Matt Groening.

Matt was leaving Nobu in Malibu this weekend ... posing for photos and signing autographs ... when our photog asked the cartoon god to finally settle the Springfield debate once and for all.

For years, Simpsons writers have given clues about the true location of Bart's hometown ... but they've never given an official answer.

But last night, Groening FINALLY gave us the answer we were looking for. Maybe.