I live in Phoenix, Arizona and work at the manufacturing facility which had a giant GE sign in the 1950's and a giant Honeywell sign up to the 1980's. We have giant parking lots.
Sometime in the late 1980's someone left a Twinkie in the parking lot next to a parking barrier. It was lying on the ground. I kept track of it . . . for several years. It turned black in the sun. I suspect it also turned very hard.
The one thing that impressed me was that birds, coyotes, and even insects left it alone to rot. They would not eat it!
That is VERY interesting.
I-17/Thunderbird, west side of the freeway?