In 1926, Northern Pacific became the first railroad to order a 4-8-4 locomotive, which is usually called a “Northern” in the NP’s honor. Other railroads had successfully used 4-8-2 locomotives, but NP needed four wheels to carry an extra large firebox because it burned a low grade of coal.

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Although American railroads constructed or purchased almost twice as many 4-8-2s as 4-8-4s, 4-8-4s ended the steam era hauling the Twentieth Century Limited, Los Angeles Limited, Chief, Coast Daylight, Empire Builder, North Coast Limited, and many other fine passenger trains, and so the public came to identify it as the premiere steam locomotive for passenger service. As a result, more than 40 4-8-4s survive today, at least 10 of which are operational, while there are only 17 4-8-2s, only one of which is operational.

In 1930, the Timken roller bearing company ordered a 4-8-4 locomotive equipped with roller bearings to demonstrate the advantages over friction bearings. Near the end of its demonstration tour, the locomotive suffered some damage while it was being operated by the Northern Pacific, so NP bought it and repaired it. NP’s first 12 4-8-4s were listed as class A, so the Timken locomotive was called class A-1.

In 1934, NP ordered another 10 4-8-4s, all of which were equipped with roller bearings. It called these class A-2 and they are described in this brochure, which I photographed at the Minnesota History Center, as “the first fleet of roller bearing steam locomotives ever built.” These locomotives also had 77-inch driving wheels instead of the 73 inches in the A and A-1 classes, and developed 250 pounds per square inch of boiler pressure instead of the 210 of the A class. For what it’s worth, they were built by Baldwin while the A and A-1 were built by Alco.

Later NP would add to its 4-8-4 fleet with the A-3, A-4, and A-5 locomotives, eventually owning 49 such locomotives. NP’s half-subsidiary Spokane, Portland & Seattle also ordered three 4-8-4s that were near duplicates of the A-3 class, differing only in that they were equipped to burn oil instead of coal. Today, the SP&S 700 is, in a real sense, the only Northern Pacific Northern locomotive left.