The photo is from the U. S. Geological Survey, but the caption there – Yellowstone National Park, Wyoming. Tourist camping scene. 1924. – is probably not entirely correct.
On the USGS site, the photographer is cited as C. E. Dobbin. It turns out that Dobbin is the man seated in the picture. Searches yielded a photo of Dobbin, but little else other than dates of birth and death, the fact he was a geologist and his first name was Carroll.
While they may have been tourists at the time of the picture – there is an open can of Del Monte sliced pineapple, a box of vanilla wafers, and other snacks on the tailgate of the truck –, it is likely that most of those in the picture were working geologists in the Yellowstone area during the summer of 1924.