General Motors Electro-Motive Division (EMD) built 4,112 GP9 locomotives between January 1954 and August 1963.
The four-axle diesel-electric locomotive generated 1,750 horsepower. An EMD 567C sixteen-cylinder engine provided the power.
EMD also built GP9 locomotives without control cabs. Those were classified as GP9B locomotives.
EMD built a majority of the engines – 3,441 – for American railroads, including the Atchison, Topeka and Santa Fe Railway, the Central of Georgia Railway, the Central Railroad of New Jersey, the Georgia Railroad and the Illinois Central Railroad.