To blaze a path on the Great Plains, one would twist some tall prairie grass and the top tufts would point the way. Rather temporary.
To the wooded east, trails were marked using trees. Some lasted 500 years or more. (Find the book—there are photos.)
In the Rockies? Rocks, maybe. Petroglyphs. Pictograms. Piles of rocks. Trees, also, I suppose, until a forest fire blazed them.
Forrest Fenn’s blaze? Wish I knew.