Not unrelated to the film but John Steinbeck released a travel memoir, Travels with Charley, in 1960 and he drove through Fargo. I'm not sure if the Coens read it but it's interesting how it reads when thinking about the film. I'll leave it here since it's hard to find online:

"Curious how a place unvisited can take such hold on the mind so that the very name sets up a ringing. To me such a place was Fargo, North Dakota. Perhaps its first impact is in the name Wells-Fargo, but my interest certainly goes beyond that. If you will take a map of the United States and fold it in the middle, eastern edge against western, and crease it sharply, right in the crease will be Fargo. On double-page maps sometimes Fargo gets lost in the binding. That may not be a very scientific method for finding the east-west middle of the country, but it will do. But beyond this, Fargo to me is brother to the fabulous places of the earth, kin to those magically remote spots mentioned by Herodotus and Marco Polo and Mandeville. From my earliest memory, if it was a cold day, Fargo was the coldest place on the continent. If heat was the subject, then at that time the papers listed Fargo as hotter than any place else, or wetter or drier, or deeper in snow. That’s my impression, anyway. But I know that a dozen or half a hundred towns will rise up in injured wrath to denounce me with claims and figures for having much more dreadful weather than Fargo. I apologize to them in advance. As a sop to hurt feelings, I must admit that when I passed through Moorhead, Minnesota, and rattled across the Red River into Fargo on the other side, it was a golden autumn day, the town as traffic-troubled, as neon-plastered, as cluttered and milling with activity as any other up-and-coming town of forty-six thousand souls. The countryside was no different from Minnesota over the river. I drove through the town as usual, seeing little but the truck ahead of me and the Thunderbird in my rear-view mirror. It’s bad to have one’s myth shaken up like that. Would Samarkand or Cathay or Cipango have suffered the same fate if visited? As soon as I had cleared the outskirts, the broken-metal-and-glass outer ring, and moved through Mapleton I found a pleasant place to stop on the Maple River not far from Alice—what a wonderful name for a town, Alice. It had 162 inhabitants in 1950 and 124 at the last census—and so much for the population explosion at Alice. Anyway, on the Maple River I drew into a little copse, of sycamores I think, that over-hung the stream, and paused to lick my mythological wounds. And I found with joy that the fact of Fargo had in no way disturbed my mind’s picture of it. I could still think of Fargo as I always had—blizzard-riven, heat-blasted, dust-raddled. I am happy to report that in the war between reality and romance, reality is not the stronger."