re: I'm just speculating here, Exactly, it was a late '60's ovation.
It has been widened to be a four-laner. That design on the 35W is obsolite now. If that was the only way to the Florida Keys, it would have been abolished years ago. We may have the Florida sea salt to combat, but Minnesota has those wicked winters. Regardless, that skelectual structure had to go. IMHO.
As a good friend of mine put it that still lives there: "Can you believe that that happened here? (meaning MN)". No, I sure can't.