Cowboys often grazed their cattle on public land. Indeed, without large amounts of public land, the cattle trails would have been impossible. (And even if the land wasn't strictly public, there was a general agreement on the right to free passage across another rancher's land on the way to market. Ranches had no fences so in effect land ownership was pretty loose.) Sodbusters threatened the existence of public land and the right to cross private land. Bottom line: cowboys could not exist in a world of fences.