Northern Pacific steam locomotive 4004 at Helena, Montana, circa 1920. Number 4004, a class Z-2 built by Baldwin in 1910, is posed with its crew. Photo by Keller, J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4004 at Helena, Montana, circa 1920. Number 4004, a class Z-2 built by Baldwin in 1910, is posed with its crew. Photo by Keller, J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4004 at Easton, Washington, circa 1928. Number 4004 is a class Z-2 built by Baldwin in 1910 J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4003 in helper service at Lester, Washington, circa 1915. Number 4003 is a class Z-2 built by Baldwin in 1910. Photo by Art Westborg, J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4003 at Easton, Washington, circa 1915. Number 4003 is a class Z-2 built by Baldwin in 1910. Photo by GW Pilgrim, J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4003 at Bozeman, Montana, on August 22, 1943. Number 4003 is a class Z-2 built by Baldwin in 1910. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4002 at Bozeman, Montana, on August 22, 1943. Number 4002 is a class Z-2 built by Baldwin in 1910. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4001 at Livingston, Montana, on August 22, 1943. Number 4001 is a class Z-2 built by Baldwin in 1910. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 4000 on September 18, 1916. Number 4000 is a class Z-2 built by Baldwin in 1910. Photo by Charles R. Iles, J.M. Fredrickson collection. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 40, circa 1878. Number 40 (old number series) was built by Baldwin in 1872. J.M. Fredrickson collection. Other Subject Classes: steam locomotive, roster photo