The GP50 is a 3,500 horsepower locomotive that was manufactured by Electro-Motive Division from May of 1980 through November of 1985. During this time period, 278 examples were manufactured for five different railroads: AT&SF, BN, C&NW, MP, and SOU.
The GP50 was the first model manufactured by EMD to be equipped with microprocessor controls and its development can be directly attributed to the success of the "experimental" GP40X model of 1978. It also served the purpose of being the response to General Electric's Dash 8 Series. It was initially offered as a higher-horsepower upgrade to the GP40-2.
Among the first to realize this was the Chicago and Northwestern Railroad. Following demonstrations of the GP50 on the C&NW, an order was placed in May of 1980 for 50 examples, CNW GP50s #5050-5099. Along with the SD50s purchased prior to the arrival of the GP50s, the GP50s served as power for high-priority trains such as intermodal services. Following in the C&NW's footsteps, the Missouri Pacific Railroad placed an order in November of 1980 for 30 examples, MP GP50s #3500-3529. Many of MP's locomotives were barely on the property before its dissolution into the Union Pacific Railroad in 1981/1982.
During the time period that MP's GP50s were brought into service, the Southern Railway, and the Atchison, Topeka, and Santa Fe Railway placed orders for GP50s. The SOU placed an order in September of 1980 for 90 "Hi-Hood" examples, SOU GP50s #7003-7092. The AT&SF placed an order in January of 1981 for 45 examples, ATSF GP50s #3810-3854. ATSF GP50s #3810-3823 were built to work in pairs in a "master-slave" configuration.
In addition to AT&SF, C&NW, MP and SOU, the Burlington Northern Railroad also made purchase of several examples of the EMD GP50. BN GP50s #3100-3109 were ordered as SLSF GP50s #790-799 but were delivered directly to the Burlington Northern Railroad in December of 1980. BN GP50s #3110-3157 were ordered and delivered from June of 1985 through November of 1985. The Burlington Northern Railroad also made purchase of five EMD GP50Ls, an extended cab variation of the GP50, BN GP50Ls #3158-3162. BN GP50s #3110-3157 were delivered in the BN's famed "Tiger Stripe" livery and were used for high-priority intermodal and freight services throughout the Midwest and Pacific Northwest.
Today, several examples of the EMD GP50 are still in service under new enterprises. The largest rosters are maintained by the BNSF, NS, and UP with several under lease ownership.
The AT&SF, BN, C&NW, MP, and SOU were the only railroads to purchase the GP50 model.
Several of the Union Pacific Railroad's GP50s, of C&NW and MP heritage, were rebuilt by Motive Power Industries with Caterpillar Engines and are classified as MP20GPs.
An extended cab version of the GP50, the GP50L, was manufactured for the Burlington Northern Railroad with the "L" designating a longer/larger cab for more crewmembers. Only five were built.