I recall seeing the Denver Post bundles, too. Were they still doing that when you were working there? I think they were for McCook or Hastings. (Note to Easterners: the "Rocky Mountain Empire" - the region that Denver dailies were circulated in - reaches to Lincoln, NE.)
People think that the internet killed country circulation of big city dailies, but before that the decline of rail passenger service and intercity bus service had made deliveries to many small towns impractical. One of the SP's steps in killing passenger trains was to replace baggage cars with next-day delivery by their trucking subsidiary. Luckily at that time there were still multiple trips a day scheduled on GL and TW bus lines and they were handed the business.