Click to see the album Big Boy Steam Locomotive in Kenefick Park, Omaha
From Wikipedia:
"Centennial No. 6900 is the largest and most powerful diesel-electric locomotive ever built. Big Boy No. 4023 is the world's largest steam locomotive.
The Big Boys were specifically designed to meet the need to pull a 3,600 short ton (3300 metric ton) freight train over the long 1.14% grade of the Wasatch Mountains in Utah and Wyoming.
The Big Boys rendered important service in the Second World War, especially since they proved so easy to fire that even a novice could do a fair job. Since many new men who were unsuited to combat service or exempted were hired by the railroads to replace crewmen who had gone to war, this proved advantageous. During the war, after German agents filed reports that the Americans had giant steam engines that were moving huge trains full of vital war material over steep mountain grades at high speed, their reports were dismissed as "impossible". Their performance in moving a huge volume of war material throughout WWII was repeatedly cited and the Big Boys are generally acclaimed as having made a huge contribution to the war effort."
Read more at Big Boy Steam Locomotive #4023 in Kenefick Park, Omaha from Hit the Road - See America and the World.