I hitchiked the middle portion (Wyoming to Chicago) several times i the early '60's; I don't think there were any Intertate system pieces there yet.    I slept by the side of the road, washed up in gas station restrooms, got rides with radical farmers and striking railroad telegraphers as well as Mormons who warned me of the vicious Eastern cities they had never seen. It was almost all two-lane, and always friendly. Of course, in memory I was never cold, hungry, tired, or discouraged.   The experience probably imporves in the retelling.