Maine Central Railroad Class P locomotives were originally intended for heavy freight service.
They were transferred to branch line service as replaced by class O 4-6-0 locomotives beginning in 1903.
American Locomotive Company produced the last six of the class at their Manchester plant in 1902.
Builders numbers 25442 through 25445 were 7,600 lb (3.4 tonnes) heavier than the Schenectady locomotives and generated 1,300 lbf (5.8 kN) more tractive effort.
The P&RF engines which became Maine Central numbers 320 and 321 were 21,000 lb (9.5 tonnes) heavier than the infobox specifications and generated 8,800 lbf (39.1 kN) more tractive effort.