It's interesting how the whole Western thing was so transient, on the cusp of twentieth-century modernity as Peckinpah points out. So that I think the whole genre is somewhat elegiac: what Wayne and Peckinpah have in common.

As it's often been pointed out by economists and historians, the developed world changed utterly between the end of the US Civil War--when steel was still so scarce that fence railings were made of wood and much of the Western range therefore unfenced, as in "Don't Fence Me In"--and 1900: by which time we had fencing wire, not to mention enormous steel ships, the modern chemical industry with its steel pipes and pressure vessels, the petroleum industry, automobiles, and so on.

And it didn't stop. If the Wild Bunch had stuck around a bit longer, they would have been in the Jazz Age. Of course as Peckinpah suggests we wouldn't really want to go back. Not really.