In 1941 The Union Pacific Railroad Company built 25 of the largest steam locomotives ever made. The Big Boy could pull a train a mile long moving 70 miles an hour on flat ground. The Big Boys were taken out of service in 1962.After World War II, people began to use diesel engines more than steam engines. Diesels were stronger, cleaner, and worked better than steam engines. Steam engines began to disappear from the railroads. By 1960 there were only a few steam engines used.The Japanese build the first "High Speed Train". This train could travel 125 miles an hour. The Japanese called their new train the "Shinkansen". Shinkansen means "new trunk line" in Japanese.