That sounds like the same cross-country journey told about in "No One Here." I forget the friend's name and don't have the book in front of me. The one anecdote that particularly stands out in my mind is Jim and his young friend getting picked up by an older woman when hitch-hiking. She propositions them and the friend kiboshes the deal because he's so frightened!
OT: dang, this thread is wandering all over the place - love it!
Sorry I missed this first time around. I only read NOHGOA once, in 1980 when it was first published, then I tore it to shreds and threw it out in a rage.
If this story is in it I may just have to pick up another copy. Maybe. One of these days...