[Thanks to Jimmy]The American West, 150 Years Ago, photo essay. Photos by Timothy O'Sullivan.
(Notice that you can now get even bigger pictures in these photo posts, selectable just above the first image.)
Now that is one hard-working photographer! Apart from the hardships of the wild west in general, and moving around in such a landscape, I think in those days they only had wet-plates to photograph on, which means that he had to pitch a tent with a darkroom whenever he wanted to take a photo, and develop the photo straight out of the camera. (Picture 12 shows his darkroom wagon.)