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.
New York Central Niagara
The American Locomotive Company ALCO proposed these locomotives, and although the design owes something to the Union Pacific 4-8-4's, of which Union Pacific 844 is the best-known, the design was actually quite new. Some steam experts have claimed the Niagara to be the ultimate locomotive, as it had the speed of an FEF (the Union Pacific's nickname for their 'four eight fours' was FEF) and the power of Northerns with smaller driver wheels.