During the 1970s many railroads were rebuilding their fleet of early locomotives such as their EMD GP7s and GP9s. EMD saw an opportunity to
provide an alternative that alleviated the need for railroads to do their own rebuilding. In 1976 the GP15-1 was announced. EMD made use of
major components from trade in locomotives to provide a cost-effective way to provide what was essentially a new locomotive at a much lower
price. Missouri Pacific was the first railroad to purchase the GP15-1, and with subsequent purchases accumulated well over 100. Conrail was the
next largest customer with 100 being added to their roster in 1976. Built from 1976 to 1982, many of the GP15-1s (and its variants such as the
GP15T and GP15AC) remain in service today in yard or branchline duty.