The Four Sixes ranch does exist off-screen, as stated in the episode. It was founded in West Texas by the Burnett family in 1870, and occupies an entire county. Quite recently, it was sold by the Burnett family trust to Taylor Sheridan, who played Travis in this episode and also the executive producer (otherwise known as the showrunner) , and a real-estate investment group for 350 million dollars. Also, there is news about a potential spin-off called 6666 (2024).
Large four-legged animals will not walk over a cattle guard because they realize that their feet would slip and fall through the gaps between the metal slats, causing them to get stuck and/or injure themselves. The design of a "cattle guard" allows for an opening to be left in a fence for vehicles to drive through freely without the need of a gate to open and close every time, while preventing animals from passing through. They are used to inhibit the passage of animals like horses, moose, deer and, obviously, cattle.
There was a post script to John Prine at the end of the episode, after his song "Caravan of Fools" played
An Ag-Exemption, or Agriculture Exemption, refers to programs enacted by the state to help reduce the tax burden that farmers and ranchers face. These exemptions include lowering property taxes and reducing or eliminating sales tax. The exemptions affect land use classifications and the sale of agricultural machinery, equipment, parts and supplies.
In Roy Rogers final movie, Mackintosh and TJ (1975), the name of the ranch where they worked for Jim Webster was the "6666". This was also a cattle ranch and located in Texas. Coincidentally, one of the locations for shooting this film was at the
Four Sixes Ranch - 1102 W. U.S. Highway 82-114, Guthrie, Texas.