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
In the 20th century, Chief Mechanical Engineer of the London and North Eastern Railway (LNER) Nigel Gresley designed some of the most famous locomotives, including the "Flying Scotsman", the first steam locomotive officially recorded over 100 mph in passenger service, and a LNER Class A4, 4468 "Mallard", which still holds the record for being the fastest steam locomotive in the world (126 mph).