Mainline steam trains in Great Britain
The most famous steam locomotive operating on the British main line is the 1923 built "Flying Scotsman". After being taken into public ownership in 2004, following a decade long refit it returned to mainline service in 2016. The fastest steam locomotive ever built, the 1938 built "Mallard", was also certified for main line operation briefly in the 1980s.
Santa Fe class 3460
In December 1937, locomotive #3461 set a world record for the longest single run by a steam locomotive by completing the from Los Angeles, California to Chicago without maintenance other than five refuelling stops en route, hauling Train #8, the Fast Mail Express. An average speed of was obtained, including stops; maximum speed during the run was . During steeply graded portions of the run it was, of course, assisted by helper locomotives. Such long distance runs were a goal of railway operating departments, enabling a reduction in locomotive numbers and through increased locomotive utilization, reduce overall costs.