EMD can lay claim to being the company that ended the dominion of the steam locomotive on the world's railroads, by both producing high-quality, reliable locomotives, and just as importantly (maybe more so) knowing how to sell them. That the victory of the diesel locomotive over the steam locomotive was, outwardly, such an easy and rapid one is thanks to the marketing and sales skill of EMD, backed by its aggressive and confident corporate parent.
The origins of what were to become EMD were in 1922, when H.L. Hamilton and Paul Turner founded a company they called Electro-Motive Engineering in Cleveland, Ohio. The next year, the company sold only two gasoline-powered rail motor cars, one to the Chicago & Great Western and the other to the Northern Pacific. They were delivered the following year, and worked well - fortunately for the fledgling company, because the sales were conditional on satisfactory performance. The next year, 1925, the company changed its name to Electro-Motive Corporation (EMC) and entered full-scale production, selling 27 railcars.
In 1930, General Motors, seeing the opportunity to expand into a new field ripe for the picking, purchased the company and also its engine supplier, Winton Engine. Advancing from railcars, the company began building multi-car diesel streamliners, for the Union Pacific among others. By 1935, GM felt confident enough to invest in a brand new factory in La Grange, Illinois, which is still the corporate headquarters. By the end of the 1930s, EMD had a diesel engine powerful and reliable enough for road locomotive use; the new technology found its first uses in glittering prow-nosed passenger locomotives, but EMD's eye was on the meat - freight service. The glamorous passenger services made little money for the railroads; capturing the freight market from the steam locomotive would be the ultimate prize. The company produced a multi-unit freight locomotive demonstrator, the EMD FT, and began a tour of the continent's railroads to demonstrate it.
The tour was a success; Western roads in particular saw their prayers of freeing themselves on their dependence on scarce, expensive desert water supplies for steam locomotives answered in the FT. By 1940 EMD was producing a locomotive a day and had reached 600 in service.
The Second World War temporarily stopped EMD locomotive production - the diesel engines were instead required in Navy ships - but in 1943 production of locomotives restarted. More locomotives were needed to haul wartime supplies. The war, however, was in the end a godsend for EMD; while it was allowed to continue to develop the diesel locomotive and to sell it to railroads, its competitors in the locomotive industry - principally the American Locomotive Company (Alco) and the Baldwin Locomotive Works - were prohibited from any work with diesel locomotives. They were instead ordered to produce steam locomotives to pre-existing designs, as fast as they possibly could. This delayed EMD's competition and dealt them what was in the end a fatal blow. By the end of the War, EMD's diesel production was in full swing, with a new improved freight locomotive in production, the EMD F3, as well as new passenger E-Units.
The story of diesel's conquest of steam is better placed elsewhere, but a combination of many factors weakened steam's position and strengthened that of the diesel locomotive, and by the late 1940s to early 1950s, the majority of American railroads had decided to dieselize. While other builders had entered the diesel locomotive field - whether old steam builders like Baldwin, Alco and Lima, or newer competitors like Fairbanks-Morse, also a producer of Navy diesels in the war - EMD's extra years of experience told. Most railroads ordered a few units from several different builders in their first, trial purchase -- but the second, volume order more often than not went to EMD. Most of these were sales of its freight F-Unit platform - the EMD F3 and later EMD F7 - but their passenger E-Unit locomotives just as quickly replaced their steam counterparts with shiny new EMD E7 and later EMD E8 locomotives. The economic arguments for diesel over steam were a bit shakier than those for freight service, but it hardly mattered - passenger service was more a matter of rolling advertisements and publicity machines than actual profit by this late date, and what railroad wanted to be behind the times?
In 1949, EMD introduced a new, revolutionary locomotive - the EMD GP7. Called a road-switcher type, its design was that of an expanded diesel switcher, with the diesel engine, main generator and other equipment in a covered, but easily removed, hood (thus the other name for these locomotives, hood units). This hood being narrower than the locomotive, this enabled the crew to have visibility in both directions from a cab placed near to one end. The structural strength in the road-switcher was in the frame, rather than in a stressed carbody in earlier locomotives. The maintenance ease of this new type of locomotive won over the railroads in short order - faster, indeed, than EMD truly expected. With very few exceptions, all locomotives produced in the United States for domestic use since the 1960s have been hood units.
One by one, EMD's competitors bowed out of the race. Lima failed first, merging with Baldwin and engine builder Hamilton in Baldwin-Lima-Hamilton or BLH, but the Baldwin-led company didn't last too much longer. Fairbanks-Morse, after producing a series of innovative locomotives that sold poorly, left the locomotive field (the company is still in business, in its original markets). Before long, only Alco remained, aided by the industrial might of General Electric, who manufactured the electrical gear used in Alco diesel-electric locomotives. In 1959, however, GE's patience with Alco was running thin; they appeared unable to compete with EMD, and in that year GE announced that it was going to enter the road locomotive field itself. It would still supply Alco, but not exclusively.
By 1960, dieselization of American railroads was effectively complete. EMD had won. The 1960s saw EMD consolidate their position as the dominant locomotive builder in the USA; new, high power locomotives, like the 3000 horsepower EMD SD40 and the 3600 horsepower EMD SD45 were produced and proved highly successful.
In 1969, Alco left the locomotive field, leaving GE as EMD's only domestic competitor (Montreal Locomotive Works continued to produce Alco designs under license in Canada). 1969 also saw EMD produce the most powerful diesel-engined locomotives to date; the twin-engined, 6600 horsepower EMD DDA40X Centennial locomotive for Union Pacific.
In 1972, EMD introduced computer control systems with the 'Dash-2' line; the EMD SD40-2 became possibly the most successful locomotive design in history. 3,945 were built; if the other SD40 class locomotives are included, a total of 5,752 were produced. The vast majority are still in service on American railroads. Later, in the 1980s, EMD's computer control systems on locomotives became more advanced, with computer controlled wheelslip prevention among other systems.
The early 1990s saw EMD introduce two new innovations; AC electric transmission for increased reliability and tractive effort at low speeds, and the radial steering truck which reduced wheel and track wear. The decade also saw locomotives increase in power to 6000 horsepower from a single prime mover, in the EMD SD90MAC-H locomotive.
1999 saw Union Pacific place the largest locomotive order in history - and it went to GM EMD, for the EMD SD70M locomotive.