The Chicago and North Western Railway class J was a class of 310 American 2-8-2 locomotives. They were built between 1913 and 1923 by the American Locomotive Company. In addition, the Chicago, St. Paul, Minneapolis and Omaha Railway (the Omaha Road) acquired 32, and also classified them as class J.
The locomotives had boiler pressed to feeding steam to two cylinders that had a bore and a stroke. These were connected to driving wheels. The locomotives weighed .
The first 224 locomotives, built 1913 to 1919 had Baker valve gear, the last 118, built 1921 to 1923 had Young valve gear.
The locomotives were built by the American Locomotive Company at their Schenectady, Richmond, and Dunkirk, plants.
They were used system-wide on freight trains, and became the principle freight-hauling locomotive on the railway.
The last seven locomotives built were equipped for oil firing from new; at least 18 more were retro-fitted in the 1930s and 1940s. These locomotives were used in Nebraska and Wyoming.
When new, the locomotives were hand-fired; in the mid to late 1930s many were rebuilt: driver diameter was increased by , boiler pressure was increased to to compensate, and a BK stoker was fitted. These locomotives were reclassified as J-A. With the onset of World War II, rebuildings ceased, but the fitting of stokers continued; these stoker-fitted locomotives were re-classed as J-S.
Also during the war, several locomotives were leased to the Seaboard Air Line Railroad.
In 1944 the Chicago and North Western Railway traded two of its class J locomotives for the Omaha Road's two J-1 2-10-2 locomotives.
Retirements started in 1942, and continued until the end of steam in 1956.
No locomotives of this class have been preserved.