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.
High-speed rail in the United Kingdom
Various claims exist for the first locomotive to break the barrier, notably the Great Western Railway's "City of Truro" (1904) and the LNER's "Flying Scotsman" (1934). Locomotive power capable of reaching has existed in Britain since 1938, when the LNER's "Mallard" broke the steam locomotive speed record.