The Electro-Motive's BL2 would be the stepping-stone for the company’s legendary early GP series, the GP7 and GP9 (two of the most success diesel locomotives ever built). The locomotive was a mix between the cab models and a standard road-switcher, a design that gave crews much better visibility during switching operations or simply shuffling cars around. The road-switcher was not something new, and was not even invented by EMD. However, the company knew there was a demand for such a design after seeing the success with Alco's pioneering RS1 of 1941. While the BL2 was not exactly what railroads had in mind it paved the way for the highly successful General Purpose series. Today, at least a half-dozen BL2s remain preserved around the country with a few still operational.
Following the success of its cab units, EMD realized that there was a market to be made in road-switchers, which at the time was mostly dominated by the American Locomotive Company (Alco) with its popular RS series. Since the BL2 not released until 1949 EMD was late to the game , nearly ten years behind Alco, which had sold more than 1,200 examples of its early RS1 and RS2 models (along their variants) by then. Additionally, both the Baldwin Locomotive Works and Fairbanks Morse were also offering their version of the road switcher; the former its "DRS" line (DRS-4-4-1000, DRS-4-4-1500, DRS-6-4-1500, and DRS-6-6-1500) and the latter the H15-44 and H20-44.
Naturally, EMD needed an answer and was not particularly happy by the fact that Alco, its direct competitor, was quickly becoming the industry leader in a market it wanted to dominate itself (road switchers). Intending to give crews increased visibility by cutting down the width of the long trailing hood and adding windows to behind the cab EMD believed that this would correct sight problems inherent with the E and F models. The BL2 ("BL" meant Branch Line) did allow crews better sight lines and was quite reliable. However, it still lacked exterior walkways, which made the locomotive more utilitarian and was available on Alco's models. Although unsuccessful from a sales standpoint the BL2 was really a mere stepping-stone for its next model, the GP series (meaning General Purpose).