The union's leader, Duppo, is usually present in the first room and can sell items to the Chosen One. He will also offer a job as a caravan guard for one of Roger Westin's cattle trails and will pay well for it.
The first room one normally enters is the smaller of the two. Duppo stands in the middle and there are benches with items for sale on top of them. There is also a small stove tucked into one corner, but nothing else that would imply that this is also Duppo's home.
The second, slightly larger room can be seen, but is inaccessible at first. One must complete missions for Merk before being allowed entry because it is his gambling operation. It has tables and chairs and also a Roulette table with a guard in a leather jacket nearby.
Stockmen's Association Headquarters appears only in Fallout 2.