Because of the structure of that crust and the variances in seasonal water flow, the BLM manages the area as an Area of Critical Environmental Concern and as a Special Recreation Management Area. In the center of the area, the salt crust is up to 5 feet thick, but that thins as you get out to the edges where the crust is maybe 1 inch thick. So the Bonneville Salt Flats cover about 46 square miles of land with a surface material that is about 90% pure table salt, the rest being mostly gypsum. Today, it is still protected as part of the California National Historic Trail. Because of the Donner-Reed tragedy, there was never any extensive use of the Hastings route. The Donner Party traveled this route in 1846 and troubles they experienced on the salt flats contributed greatly to their later misfortune high in the Sierras. In 1846 his route became part of the Hastings Cutoff, promoted by Lansford Hastings as an easier (and quicker) route to Califonia than the usual route through Idaho off of the Oregon Trail. Fremont with his expedition went straight across the salt flats, looking for a shorter route to California in 1845. There's no record, though, of Bonneville ever coming to this place that was named for him.

As was the custom in those days, he named the salt flats for his boss: Captain Benjamin L.E. Joseph Walker, another famous frontiersman, was mapping and exploring this area around the Great Salt Lake in 1833.

He'd probably heard about it before from Native Americans that he'd come across. In 1827, Jedediah Smith was returning from his first trip to California when he came across what we now know as the Bonneville Salt Flats.

Utah salt flats donner party