Back in the 60s there was no fear of identity theft or anything like that... and people in general, everywhere, were much more open and trusting... so finding someone was far, far easier. I remember once calling a Boston post office trying to track down an old friend, I had only his (very old) address. I told the postman the name and the old address, and said honestly I'm trying to track him down, and the postman just looked the friend up, gave me the new address, simple as that. I can picture Jack phoning around a few post offices in the general area of Riverton, simply asking "do you know an Ennis Delmar?" and eventually finding out, yes, he lives here... heck, the postman probably said "hell yeah, him and his missus live over the laundrymat" Jack: "what's the address? i'd like to send him a card" Postman: "don't worry, just write 'Ennis Delmar, General Delivery, Riverton, Wyoming' and it'll get to him."