#2706
Union Pacific Big Boy
🇺🇸 United States ·built by American Locomotive Company· from 1941· class of 25 simple articulated 4-8-8-4 locomotives
6 photos from Wikimedia Commons · credits & licences
- 1. UP Big Boy 4014: Morven· CC BY-SA 3.0
- 2. Union Pacific Big Boy 4000 1941: Association of American Railroads (railroad trade association)/photo by Union Pacific Railroad.· Public domain
- 3. Union Pacific "Big Boy" No. 4004 at Holliday Park - December 2018: Juan Enrique Gilardi· CC BY-SA 2.0
- 4. Union Pacific Big Boy 4-8-8-4 -4018 at Fair Park 09.2006 0: McKaby· CC BY-SA 4.0
- 5. Union Pacific Big Boy 4012 May 10th, 2021: Fan Railer· CC BY-SA 4.0
- 6. Union Pacific Big Boy 4014 in Counsman, CA: Fan Railer· CC BY-SA 4.0
what is it?
The Union Pacific Big Boy is a type of simple articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) in Schenectady, New York, between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service until July 1959. The 25 Big Boy locomotives were built to haul freight over the Wasatch Range between Ogden, Utah, and Green River, Wyoming. In the late 1940s, they were reassigned to Cheyenne, Wyoming, where they hauled freight over Sherman Hill to Laramie, Wyoming.
who runs it
base stats
Bars compare against all trains: 600 km/h (maglev), 1,700 seats; power, weight and number built on a log scale up to 20 MW, 1,000 t and 20,000 built.
fun facts
- First built 85 years ago, in 1941.
- 5.2 MW is about 61 family cars (~85 kW each) flat out.
- Weighs about as much as 58 African elephants (~6 t each).
- 25.9 m long: about 6 cars parked nose to tail.
- Served for 18 years (1941–1959).
steam locomotive: Burns coal, wood or oil to boil water; the steam drives pistons that turn the wheels.
spec sheet
- built
- 1941–1944
- in service from
- 1941
- retired
- 1959
- status
- preserved
- number built
- 25
- kind
- Steam
- traction
- steam
- origin
- 🇺🇸 United States
- builders
- American Locomotive Company
- designer
- Otto Jabelmann
- operators
- Union Pacific Railroad
- top speed
- 129 km/h
- power
- 5.2 MW
- gauge
- 1,435 mm standard gauge
- wheel arrangement
- 4-8-8-4
- length
- 25.9 m
- weight
- 346 t
From the Wikipedia infobox and Wikidata. Blank means the sources don't say.
Sources: Wikidata Q933916, Wikipedia: Union Pacific Big Boy (CC BY-SA 4.0).Updated 2026-10-25.