For many years I've wondered why the singer in Folsom Prison Blues was in jail in California when he shot a man in Reno, which is in Nevada?  Today the mystery was solved.  I'm reading Corn Flakes with John Lennon by Robert Hilburn (former rock critic for the L.A. Times for 35 years).  At one point he writes the following passage about Johnny Cash:
 
I listened to 'Folsom Prison Blues' for five decades before asking myself, if the guy in the song shot a man in Reno, what's he doing in prison in California?  When I asked John about it, he burst out laughing. 'I never did get good grades in geography.'
 
So now we know!  By the way, I strongly recommend this book.
 
Bill, tgo

It does look interesting.

Does anyone know what the exchange is between the jailhouse personnel and audience at the end of Cocaine Blues?

Maybe they were both citizens of California, the guy didn't die and sued him in a California court (which applied the law of Nevada, of course, using vested rights theory). The victim won a judgment but Cash didn't pay up so the CA courts put him in jail for contempt.  
 
Or maybe he shot him in Reno, but the guy died much later in CA and the CA courts thought, for some reason, that that was when the actual crime was committed.
 
Whaddaya think, counselor?

If he shot the guy in Reno, perhaps he fled up the pass into California where they got him on firearms charges?  *shrugs*  
 
John

Maybe it's short for Renoville or Reno Junction (both in CA)?
 
Peter

Or maybe Reno is a sideways reference to renvoi, the process by which a court adopts the law of a foreign jurisdiction with respect to any conflict of laws that arise.
 
That Cash guy is pretty deep!