The desert scenes feature shots of tall saguaro cactus. The film is set in Texas, an area in which saguaro cacti are not found (they're mostly in Arizona and New Mexico).
The film takes place in an unnamed territory with a major plot point focusing on the Governor's bid for statehood. Texas was granted statehood in 1845, decades earlier than the period depicted in this movie. Since the only connection to Texas is a long cattle drive to Abilene, process of elimination would suggest that the unnamed territory is Texas's neighbor, New Mexico, where saguaro cacti are found. See more
When factories first began to send their pall of smoke over the cities, and farmlands in the east offered only the barest living, Americans turned their faces toward the west. They poured into the new territories by thousands; bringing their household goods, fording the might rivers, and climbing the mountains. Fighting Indians and outlaws, praying, toiling, dying. It was a hard land, a hostile land. Only the strong survived. A new American breed, the Pioneer. In this forge, ...