"Astonishing Yellowstone," 1939

Yellowstone National Park, established 1872, was America's first national park. Early tourists reached Yellowstone by railroads like the Northern Pacific, producer of this guidebook. The increasing popularity of automobiles spelled the decline of Yellowstone-bound trains. The more than 4/5 of travelers that had gone by rail in 1915 had been reduced to about 1/8 by 1930.