Milwaukee Road class F7
The F7s are major contenders for the fastest steam locomotives ever built, as they ran at over daily. One run in January 1941 recorded by a reporter for "Trains" magazine saw achieved twice—in the midst of a heavy snowstorm. Baron Gérard Vuillet, a French railroading expert, once recorded a run between Chicago and Milwaukee where the locomotive reached and sustained an average for . However, the British locomotive LNER Class A4 4468 "Mallard" is officially accepted to be the world's fastest, with a run recorded at but authenticated at 126 mph in 1938.
Steam locomotive
Many of the earliest locomotives for American railroads were imported from Great Britain, including first the "Stourbridge Lion" and later the "John Bull" (still the oldest operable engine-powered vehicle in the United States of any kind, as of 1981) however a domestic locomotive-manufacturing industry was quickly established. The Baltimore and Ohio Railroad's "Tom Thumb" in 1830, designed and built by Peter Cooper, was the first US-built locomotive to run in America, although it was intended as a demonstration of the potential of steam traction, rather than as a revenue-earning locomotive. The "DeWitt Clinton" was also built in the 1830s.