Editing Booster engine (section)

===North America===
The booster saw most use in [[North America]].  Railway systems elsewhere often considered the expense and complexity unjustified.

Even in the North American region, booster engines were applied to only a fraction of all locomotives built.  Some railroads used boosters extensively while others did not. The New York Central was the first railroad to use a booster in 1919 and remained a proponent of the device, applying them to all of its high-drivered [[4-6-4]] [[NYC Hudson|Hudson]] locomotives to increase their acceleration out of stations with crack passenger trains.  The rival [[Pennsylvania Railroad]], however, used few booster-equipped locomotives. Similarly, the [[Chesapeake and Ohio Railway|Chesapeake & Ohio]] specified boosters on all of its [[Superpower steam|Superpower]] locomotives aside from the [[Chesapeake and Ohio class H-8|Allegheny]] to increase tonnage ratings over some of the hilly terrain found on their main lines, while rival [[Norfolk & Western]] experimented with boosters briefly and found their cost unjustified, instead choosing to increase engine tractive effort through the raising of boiler pressure.

[[Canadian Pacific Railway]] rostered 3,257 steam locomotives acquired between 1881 and 1949, yet only 55 were equipped with boosters. 17 [[Royal Hudson|H1 class]] 4-6-4s, 2 K1 class [[4-8-4]]s and all 36 [[Selkirk locomotive|Selkirk]] [[2-10-4]]s.