| UP 4001 rolls through the yard at Ogden in mid 1946. 4001 was the second of 20 Big Boys ordered by Union Pacific in 1941. The last of these 20 massive engines was built in December 1941, but another five would be built in 1944 to meet wartime traffic demands. All 25 of these brutes would be retired by 1960, and of them, 17 (including the 4001) would be scrapped in the following 3 years. Obtained from Union Pacific Steam: Big Boy Portraits (Bush, Ehernberger) |