The mechanical design of the GG1 was based largely on the New Haven EP3, which had been borrowed earlier from the New Haven Railroad by the PRR to compare it to its current standard electric locomotive, the P5a.
Beginning in the early 1910s, the Pennsylvania received the FF-1 but decided it was too slow for passenger trains and was relegated to heavy freight service. In 1933, the PRR decided to replace its P5a locomotives and told General Electric and Westinghouse to design prototype locomotives with the following specifications: a lighter axle load and more power than the P5a, a top speed of at least 100 miles per hour (160 km/h), a streamlined body design and a single (central) control cab. Both companies delivered their prototypes to the PRR in August 1934. Both locomotives had the distinctive streamlining, but #4800 was the only unit ever to have a riveted body, giving rise to the nickname "Old Rivets".
The GG1's entered service with the PRR in 1935 and later ran on successor railroads Penn Central, Conrail and Amtrak.
The last GG1 was retired by New Jersey Transit in 1983 and most have been scrapped, but 16 of these engines remain in museums. None will ever run again given the removal of the transformers upon retirement, for these were revealed to contain dangerous materials known as PCB's; that was one of the factors for the GG1's demise, apart from bogie and frame cracks.
- Some GG1's were painted in Amtrak's livery of red, white and blue— the colours of the American flag.
- Beginning in the early 1910s, the Pennsylvania received the FF-1 but decided it was too slow for passenger trains and was relegated to heavy freight service. In the mid 1920s, they received the L5 electric which had third rail power supply at the time.
- In 1976, locomotive #4800 was painted in patriotic colors to celebrate the United States Bicentennial celebrations.
- In 1969, Locomotive #4902 hauled the Golden Spike Centennial Limited.
- These electric locomotives are also used for freight service besides passenger trains.
- In 1952, the paint scheme was changed to tuscan red; three years later, the pinstripes were simplified to a single stripe and large red keystones were added.
- Both companies delivered their prototypes to PRR in August 1934.
- The first designer for the GG1 project was industrial designer Donald Roscoe Dohner, who produced initial scale styling models, although the completed prototype looked somewhat different.
- In later years, after when locomotive #4902 hauled the Golden Spike Centennial Limited the locomotive became Amtrak #905.