A 2-8-8-4 steam locomotive, under the Whyte notation, has two leading wheels, two sets of eight driving wheels, and a four-wheel trailing truck. The type was generally named the Yellowstone, a name given it by the first owner, the Northern Pacific Railway, whose lines run near Yellowstone National Park. Seventy-two Yellowstone-type locomotives were built for four U.S. railroads. Other equivalent classifications are: The equivalent UIC classification is, refined for Mallet locomotives, (1′D)D2′.