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.
Russian locomotive class Ye
In 1944 the first steam engines of the Е series, which was given index "a" (U.S.), resulting in the designation of Еа. The numbers of locomotives built by ALCO began at #2001 and the Baldwin built locomotives at #2201. In September the same year, the first Baldwin built locomotive (Еа-2201) was sent to the pilot ring VNIIZhT which was tested until October. In the course of the tests, it was found that forcing the boiler to , a cutoff of 60% and at a speed of , the engine could develop of tractive effort. It was also found that the locomotive could achieve , which was a 20–25% increase compared to the World War I engines (). The improved performance was achieved through improved boiler and the use of mechanical stoker. The temperature of superheated steam was typically 572–644 °F (300–340 °C), and no more than 698 °F (370 °C).