First authored by OConnor- Henry Roe Campbell (September 9, 1807 – February 6, 1879) was an American surveyor and civil engineer. Campbell contributed to American railroading and bridge-building in the first half of the 19th century. Campbell patented his 4-4-0 design in February 1836,[1][2] just a few months before the patent law was changed to require that claims include proof of originality or novelty.[3]

The 4-4-0 or American type steam locomotive was the most popular wheel arrangement in 19th century American railroads and was widely copied.[2] White noted that the design was successful because it .."met every requirement of early United States railroads".[2]

At the end of Campbell's career. a Harper's Magazine article in March 1879 noted that the impact Campbell's design played in railroad development in the United States when it wrote...

"English railroads were short, solid, straight and level, and laid with the best rails in the world ; and their massive and powerful, and rigid-framed engines are thoroughly adopted to those perfect roads. On the contrary, the American road is generally of great length, and being necessarily cheap it "goes as you please." Over these eccentric roads the American locomotive adjusts itself to every change of level both across and along the line ; it takes curves that would be impossible for the rigid English engine ; and, finally, it runs over a crazy track, up hill and down, in perfect safety. It has been well said that all that the English engine can do on a perfect road the American (4-4-0) engine will do ; and much more than this, it will do work on any road, however rough, hilly, curved and cheap."[4]

Not only did the new American Type steam locomotive deliver more horsepower, tractive effort, and reliability it also laid the groundwork for locomotive engineering in the 19th century with boilers mounted horizontally (instead of vertically), smoke stacks mounted vertically at the front to expel the smoke and cinders away from the crew and passengers.

This design also provided greater protection with an enclosed cab and many other features including things like cowcatchers, front-mounted headlamps/lights, etc.).

While Campbell's 4-4-0 design was less attractive by the end of the 19th century as more powerful locomotives took their place such as the 4-6-0 wheel arrangement and Consolidations of the 2-8-0 wheel arrangement even though some 4-4-0s remained in service into the 1940s, over 100 years after the design was initially conceived.