I'd gather, when many pronounce the name, the middle transitional syllable is somewhat lazy, and the result is closer to Ore-gun, than otherwise. I happen to concur with this guy: David Harris B.S. Psychology & Counseling, University of Oregon Answered 2 years ago Ore-gun https://www.quora.com/How-do-you-pronounce-Oregon-Ive-heard-both-Ore-gone-and-Ore-gun
a soft 3, which could be considered 2.5 It's somewhere between Organ and Or eh gun, with the "eh" being barely perceptible.
When I lived in New Jersey, everyone in Ft. Monmouth pronounced it Tren- ton, including the one in my platoon who was born and raised in New Jersey.
It appears somewhat logically correct but definitely not phonetic. The correct international phonetic pronunciation of the 'ee' sound is 'i'. I learned that from my Korean teacher who acted as the interpreter for the President of South Korea when he visited Seattle.
Just don't pronounce it Oree-gone, which drives me temporarily insane. You might not like me in that state if you're the one who pronounced it that way.