What is union pacific 9000?

Union Pacific 9000, also known as the "Big Boy" locomotive, is a type of steam locomotive built for Union Pacific Railroad (UP) from 1941 to 1944. It was designed mainly to haul heavy freight trains over steep mountain grades in the western United States, specifically between Ogden, Utah, and Cheyenne, Wyoming.

The Big Boy locomotive is one of the largest steam locomotives ever built, measuring 85 feet long and weighing over 1 million pounds. It was powered by a four-cylinder compound steam engine, producing 6,290 horsepower, making it capable of pulling a 5,000 ton train up a 1.14% grade at 25 mph.

Union Pacific ordered a total of 25 Big Boy locomotives, and they were numbered 4000-4024 and 9000-9014. The locomotives were retired from service in the 1950s and 1960s due to the decline of steam power and the rise of diesel locomotives.

Today, eight Big Boy locomotives are preserved in museums, and Union Pacific 4014 was restored to operation in 2019 for a "Great Race Across the Midwest" tour to celebrate the 150th anniversary of the transcontinental railroad.