Verified answer

There are two TRAINS of thought on this.

The American record is held by the the A class Atlantics (4-4-2) built in 1935-37 by Alco for the Milwaukee Railroad.

This locomotive was recorded at 120+ mph.

The European record is held by the German's streamlined 4-6-4 Hudson (4-6-4) # 05 002. It achieved a recorded speed of 124.5 mph.

The article below has all of the details on these steam locomotives...

There are also those folks who claim the record should go to the locomotive that could sustain high speeds over long runs.

That would put the Norfolk & Western's J-Class (4-8-4) up there at 110+ mph. This was also the last steam engine to run on a regular schedule in the United States.

126 mph

http://www.o-keating.com/hsr/mallard.htm

thanks for the question it was fun.

this is just the A4, but england had the fastest steam engines clean through to the 1960's, the A4 was the fastest in Britain, ergo.....

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