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2-4-4 Mason Bogie locomotive #6 on the Boston, Revere Beach and Lynn Railroad as built in 1886.
This article is about the steam locomotive type. For the football formation see Formation (football).

In Whyte notation, a 2-4-4 is a steam locomotive with two unpowered leading wheels followed by four powered driving wheels and four unpowered trailing wheels.

The equivalent UIC classification is 1'B2' (or (1'B)2' for a Mason Bogie).

This type of locomotive was one of the more common configurations for Mason Bogie locomotives, like those used on the Boston, Revere Beach and Lynn Railroad.