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 Sydney, Clyde Engineering and the workshops in Eveleigh both built steam locomotives for the New South Wales Government Railways. These include the C38 class 4-6-2; the first five were built at Clyde with streamlining, the other 25 locomotives were built at Eveleigh (13) and Cardiff Workshops (12) near Newcastle. In Queensland, steam locomotives were locally constructed by Walkers. Similarly the South Australian state government railways also manufactured steam locomotives locally at Islington Railway Workshops in Adelaide. Victorian Railways constructed most of their locomotives at their Newport Workshops and in Bendigo, while in the early days locomotives were built at the Phoenix Foundry in Ballarat. Locomotives constructed at the Newport shops ranged from the nA class 2-6-2T built for the narrow gauge, up to the H class 4-8-4 – the largest conventional locomotive ever to operate in Australia, weighing 260 tons. However, the title of largest locomotive ever used in Australia goes to the 263-ton NSWGR AD60 class 4-8-4+4-8-4 Garratt, built by Beyer-Peacock in the United Kingdom. Most steam locomotives used in Western Australia were built in the United Kingdom, though some examples were designed and built locally at the Western Australian Government Railways' Midland Railway Workshops. The 10 WAGR S class locomotives (introduced in 1943) were the only class of steam locomotive to be wholly conceived, designed and built in Western Australia, while the Midland workshops notably participated in the Australia-wide construction program of Australian Standard Garratts – these wartime locomotives were built at Midland in Western Australia, Clyde Engineering in New South Wales, Newport in Victoria and Islington in South Australia and saw varying degrees of service in all Australian states.
The introduction of electric locomotives around the turn of the 20th century and later diesel-electric locomotives spelled the beginning of a decline in the use of steam locomotives, although it was some time before they were phased out of general use. As diesel power (especially with electric transmission) became more reliable in the 1930s, it gained a foothold in North America. The full transition away from steam power in North America took place during the 1950s. In continental Europe, large-scale electrification had replaced steam power by the 1970s. Steam was a familiar technology, adapted well to local facilities, and also consumed a wide variety of fuels; this led to its continued use in many countries until the end of the 20th century.