A question has come up under Worldwide Railfan about speedometers on steam locomotives. In the U. S., about when did steam locomotives begin to be equipped with speedometers?
I don't know when speedometers/speed recorders were first put on steam engines.
However, when I worked for the New York Central I had the pleasure of taking
many cab rides in NYC diesels. Even though the engines were equipped with
good speedometer/speed recorders most of the "old head" engineers still used
their pocket watches and mile posts to time their speed. This was in the early
1960s.