For more detailed location descriptions (in lieu of driving directions), see the "Locations" section on the individual city pages. Note that those might not yet exist for all cities.
The achievementBuffalo Bill requires the player to complete 10 perfect deliveries (no damage, no fines, in-time) of live cattle to both Bushnell Farms auctions in Wyoming. One is located in Riverton and the other in Sheridan. With the addition of Cody since the 1.45 update, the player can also deliver live cattle to the auction in said city, and the achievement progress will be counted.
Trivia
Bushnell Farms first appeared in the 18 Wheels of Steel series with the same purpose. Its logo originally had a yellow background with the bull having white horns instead of yellow ones and Bushnell Farms in green text.