Northern Pacific steam locomotive 5121 waiting for disposition at Missoula in Montana, circa 1955. Number 5121 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5116 at Missoula, Montana, on August 21, 1943. Number 5116 is a class Z-6 built by Alco-Schenectady in 1937. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5113 at Missoula, Montana, on September 02, 1953. Number 5113 is a class Z-6 built by Alco-Schenectady in 1937. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5112 at Missoula, Montana, on August 20, 1949. Number 5112, a class Z-6 built by Alco-Schenectady in 1937, is on the turntable at the roundhouse. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, turntable

Northern Pacific steam locomotive 5112 at Missoula, Montana, on August 20, 1949. Number 5112 is a class Z-6 built by Alco-Schenectady in 1937. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5110 at Missoula, Montana, on August 20, 1943. Number 5110 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5104 at Missoula, Montana, on August 19, 1943. Number 5104 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5103 at Missoula, Montana, on August 19, 1943. Number 5103 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5101 at Missoula, Montana, on September 02, 1953. Number 5101 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific (NP) 5100, the first class Z-6 locomotive delivered to the NP in 1936, passes the depot at Missoula, Montana, with an eastbound extra freight in 1953. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train, passenger depot.