The S-4 was first produced in Canada, with ALCO production beginning in June 1949.

[citation needed] They were a success, with many remaining in service today.

[2] The locomotives' exterior was styled by ALCO engineer Ray Patten, who used curves in a mild application of Art Deco principles.

The S-2 and S-4 are distinguishable externally from the very similar S-1 and S-3 660 hp (492 kW) switchers in that they have a larger exhaust stack with an oblong base and a larger radiator shutter area on the nose sides.

The S-2s include former C&O 5029, B&O 516 Ontario Northland 1202 and 1201, and Seaboard Air Lane 1428 and 1431.

5109 recently was repainted into its original Chesapeake and Ohio colors in September 2013.

[4] An ALCO S-2 built in 1946 was serving the Columbia & Reading Railway as No.

25 (also former Belt Line) was disabled and put on static display outside the yard in 2019.

[2][6] An S-2 of D&RGW heritage survives on the Big South Fork Scenic Railway, as number No.

Southern Pacific 1474 is in operation, in rotation, at the Orange Empire Railway Museum in Perris, California, pulling a tourist train on weekends.

[2] The Cooperstown and Charlotte Valley Railroad operates a pair of restored ex-Canadian National units S-4 No.

104 were operational on the tourist passenger and maintenance of way services between Milford and Cooperstown, New York.

The coal-hauling Beech Mountain Railroad in Alexander, West Virginia, rosters an S-2 (No.

[7] The Minnesota, Dakota and Western Railway operates five S-2 locomotives, MD&W Nos.

[2] In the mid-1960s, Hamersley Iron purchased an S-2 for use in the Pilbara region of Western Australia.

1,[11] which was used to switch freight at NASA's Kennedy Space Center.

[12] In June 2023, the Western Maryland Rail Heritage Foundation called for donations to relocate an S-2 that was on a siding in Canada.