The fastest way to travel long distances in the beginning of the 20th century was by railroad. Railroad companies competed to attract business and vacationing travellers by advertising in brochures and issuing postcards. The postcards included railroad logos and descriptions of Western adventures that travellers would experience by booking with a particular rail line. The Northern Pacific Railroad and Chicago, Milwaukee & St. Paul Railroad have provided some of the most captivating images of the unique Yellowstone National Park (YNP) hydrologic, geologic, and geothermal features. The Union Pacific Railroad built the full-scale Old Faithful Lodge at the Panama-Pacific International Exposition of 1915; the National Park Service data show the YNP attendance more than doubled in that year. Both the Union Pacific Railroad and Burlington Route provided high-quality postcards to promote their routes to visit YNP. The Burlington Route and Northern Pacific Railroad included American Indian-related postcards for diversity.