ALCO built No. 4014 in November 1941 and delivered it the following month to Union Pacific, which placed it in revenue service. No. 4014 was part of the first group of 20 Big Boys, classified as 4884-1. Designed to haul 3,600-short-ton (3,214-long-ton; 3,266 t) trains over Utah's Wasatch Range, No. 4014 and the 24 other Big Boys routinely pulled trains of up to 4,200 short tons (3,750 long tons; 3,810 t). No. 4014's last routine repairs took place in 1956.

No. 4014 completed its final revenue run on July 21, 1959, just hours before the last revenue run by any Big Boy. It had traveled 1,031,205 miles (1,659,564 km) during its twenty years of revenue service. Union Pacific retired No. 4014 on December 7, 1961. All of the Big Boys were retired by 1962, their duties assumed by diesel locomotives and gas turbine-electric locomotives (GTELs). That same year, Union Pacific donated No. 4014 to the Southern California chapter of the Railway and Locomotive Historical Society in Pomona, California, where it became one of the eight Big Boys preserved around the United States.