Super interesting project you should know about if you don’t already: Rephotographic Survey Project. Read about it here

Left: Timothy O’Sullivan, 1872, “Green River Cañon, Upper Cañon, Great Bend, Uinta Mountains. The Horseshoe and Green River below the bend from Flaming Gorge Ridge” (U.S. Geological Survey). Right: Mark Klett for the Rephotographic Survey Project, 1978, “Flaming Gorge Reservoir from above the site of the Great Bend, Utah.”