Union Pacific Railroad steam locomotive number 4024, circa 1950. UP 4024 parked at an engine terminal. Photo by Blackie Moser, J.M. Fredrickson collection. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 4019, circa 1950. UP 4019 moves in an engine terminal. Photo by Blackie Moser, J.M. Fredrickson collection. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 4004 on display at Cheyenne, Wyoming on July 29, 1986. UP 4004 rests in a park at Cheyenne Wyoming in 1986. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 4004 on display at Cheyenne, Wyoming on July 29, 1986. UP 4004 rests in a park at Cheyenne Wyoming in 1986. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 4004 on display at Cheyenne, Wyoming on July 29, 1986. UP 4004 rests in a park at Cheyenne Wyoming in 1986. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 4004 on display at Cheyenne, Wyoming on July 29, 1986. UP 4004 rests in a park at Cheyenne Wyoming in 1986. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 3981, undated. UP 3981 on passenger train 457 or 458 using the Milwaukee line between Seattle and Tacoma. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, passenger train.

Union Pacific Railroad steam locomotive number 3977 at Seattle, Washington, circa 1947. UP 3977, a 4-6-6-4, with the Portland train at Seattle circa 1947. Photo by Blackie Moser, J.M. Fredrickson collection. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 3975 at Tacoma, Washington, in 1947. UP 3975 at Tacoma Union Station with passenger train No. 457 in 1947. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.

Union Pacific Railroad steam locomotive number 3975 at Tacoma, Washington, in 1947. UP 3975 at Tacoma Union Station with passenger train No. 457 in 1947. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive.