LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable, and one of the class, 4468 "Mallard", holds the world record as the fastest steam locomotive. Thirty-five of the class were built to haul express passenger trains on the East Coast Main Line route from London Kings Cross via York to Newcastle, and later via Newcastle to Edinburgh, Scotland. They remained in service on the East Coast Main Line until the early 1960s when they were replaced by Deltic diesel locomotives. Several A4s saw out their remaining days until 1966 in Scotland, particularly on the Aberdeen - Glasgow express trains, for which they were used to improve the timing from 3.5 to 3 hours.
Steam locomotive
The first diesel locomotive appeared on the Central Railroad of New Jersey in 1925 and on the New York Central in 1927. Since then, diesel locomotives began to appear in mainline service in the United States in the mid-1930s. The diesel engines reduced maintenance costs dramatically, while increasing locomotive availability. On the Chicago, Rock Island and Pacific Railroad the new units delivered over a year, compared with about for a mainline steam locomotive. World War II delayed dieselisation in the US. In 1949 the Gulf, Mobile and Ohio Railroad became the first large mainline railroad to convert completely to diesel locomotives, and "Life Magazine" ran an article on 5 December 1949 titled "The GM&O puts all its steam engines to torch, becomes first major US railroad to dieselize 100%". The Susquehanna was one of the earliest railroads in America to fully dieselize by 1947 and retiring their steam locomotives by 1949. The final 2-8-4 Berkshire built was Nickle Plate Road's 779 built in 1949. The last steam locomotive manufactured for general service was a Norfolk and Western 0-8-0, built in its Roanoke shops in December, 1953. In Spring of 1960, Norfolk and Western Y6b 2190 and S1290 doused their fires for the last time in a Williamson, West Virginia roundhouse. 1960 is normally considered the final year of regular Class 1 main line standard gauge steam operation in the United States, with operations on the Grand Trunk Western, Illinois Central, Norfolk and Western and Duluth Missabe and Iron Range Railroads, as well as Canadian Pacific operations in Maine.