I remember decades ago reading a book with the following vignette, set in the 60s. The white male narrator is driving through the countryside and picks up a hitchhiking young black man. The rider is extremely polite and says very little. The driver says something positive about race relations, hoping that the country is getting better, but this makes the rider uncomfortable. He soon says "you can let me out here, this is my stop," although earlier he said he had a destination much further down the road. The man is insistent, so the driver lets him out, and realizes two things: the country has further to go than he realized, and he erred in thinking he could begin speaking of such things to a strange black man. He realized that he was a "danger" to the latter, who had no reason to trust a white stranger howsoever reassuring his words were (they might have been a trap). So it was a lesson to the narrator which he carried with him.
I thought this might have been from Steinbeck's "Travels with Charley," but I just searched two google books versions and can't find it with any of the obvious keywords; he relates a more positive, but also educational, encounter with a black rider, but this one is more talkative so it isn't the anecdote I'm recalling.