She is The Union Pacific Big girl is a legendary American steam locomotive: *Design and Specifications* 1. *Builder*: American Locomotive Company (ALCO) 2. *Year*: 1941 3. *Class*: 4000-series, 4-8-8-4 articulated locomotive 4. *Weight*: 560 tons 5. *Length*: 132 feet 10 inches (40.5 meters) 6. *Height*: 16 feet 2 inches (4.9 meters) 7. *Cylinders*: 4 high-pressure, 4 low-pressure 8. *Drive wheels*: 8 driving axles, 68-inch diameter 9. *Top speed*: 80 mph (129 km/h) 10. *Power output*: 6,290 horsepower *History* 1. *Original fleet*: 25 locomotives (4000-4024) 2. *Purpose*: Haul heavy freight trains over steep grades 3. *Operational era*: 1941-1959 4. *Retirement*: Replaced by diesel-electric locomotives *Preservation* 1. *Eight preserved*: 4004, 4005, 4006, 4012, 4014, 4017, 4018, and 4023 2. *Restoration*: Several locomotives restored to operational condition 3. *Museums*: Displayed at various railroad museums *Notable Features* 1. *Largest steam locomotive*: In terms of total weight and power output 2. *Articulated design*: Allows for tighter radius curves 3. *High-pressure cylinders*: Efficient fuel consumption 4. *Iconic design*: Symbolic of American railroading's Golden Age *Fun Facts* 1. *Big Boy* nickname originated from a worker's graffiti on the first locomotive. 2. *World War II*: Big Boys played a crucial role in wartime transportation. 3. *Speed records*: Set multiple speed records for steam locomotives. Would you like more information on the Union Pacific Big Boy's history, restoration or technical details?