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.
Pennsylvania Railroad class S1
In terms of tractive effort and drawbar horsepower, PRR S1 was the most powerful reciprocating steam locomotive ever built for passenger service in 1939. Starting tractive effort calculated in the usual way (85% mean effective pressure) comes out , but the engine used 70.6% limited cutoff (presumably to increase port openings at short cutoff), so the railroad claimed a correspondingly lower tractive effort. During a test run between Chicago, Illinois and Crestline, Ohio in December 1940, S1 managed to reach on level track with 1350 tons passenger stock behind her, which was equal to 24 postwar lightweight passenger cars. In this test run, S1 also achieved an average speed of , which was 27% faster than the average schedule speed of the route. Some publishment from Germany stated that S1 was able to reach in other road tests during the late 1940s with a lighter load behind her, but PRR never claimed this record. On Apr 19, 1941, during an excursion run organized by the Detroit Railroad Club, S1 reached on the route between Fort Wayne and Chicago. 
An article "Riding the Gargantua of the Rails" in the Dec 1941 Popular Mechanics Magazine cites a speed recorded by assistant road foreman Charlie Wappes of the Fort Wayne Division during the S1’s test runs at with 12 heavyweight passenger cars in its back. There are other stories of the S1 reaching or exceeding . In the German trade press and literature from 1945, there was a report of a record run of the S1, citing railroad officials of Interstate Commerce Commission that a speed of was reached when the engine was trying to make up time for a delayed westbound train, the Trail Blazer.