When looking over the 1960 Jeep Cavalcade brochure, I noticed it was the 3rd annual event. However, the 1959 brochure doesn’t mention it being the 2nd annual event. A newspaper clipping from 1958 solved that question. It turns out there was a 1958 advance trail exploration in 1958 to prep for the 1959 event, though it seems to have been more of a low key event when compared to the 1959 and 1960 cavalcades. This short newspaper article in the June 1, 1958, issue of the Fort Collins Coloradoan explains it:
This article appeared in Grand Junction’s Dailys Sentinenl on August 23, 1959: