Several stretches of I80 and I40 here in Utah where it is legal to ride a bicycle on the freeway. No other way through.
Yes I know - insane.
I’ve bicycled on Interstate Highways in the western U.S. states, where, as you indicate, it is legal to do so along certain clearly posted sections. However, bicycles are restricted to the interstate shoulder, which is quite wide, and is relatively safe. Any bicyclist riding in a travel lane of an Interstate Highway has a death wish.