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.
LNER Peppercorn Class A1 60163 Tornado
If running is achieved, "Tornado" would also become the second fastest operational steam locomotive in the world. Regular steam operation was last seen in Britain in 1967 with the Merchant Navy class Pacific locomotives operating on the Waterloo to Bournemouth route. The fastest operational steam locomotive in the world is Deutsche Reichsbahn 18.201, allowed to run in Germany up to .