In 1933, the Pennsylvania Railroad decided to replace the P5, and instructed General Electric and Westinghouse to design an electric locomotive that was more powerful than the P5, capable of speeds of 100 miles per hour (161 km/h), have a lighter axle load and to be double-ended with a cab in the center of the carbody.
Westinghouse designed the R1 #4800, and General Electric submitted the GG1, then numbered 4899.

The frames, running gear and riveted body for the prototype GG1 were built by Baldwin Locomotive Works.
The partially built locomotive was then shipped to the General Electric factory in Erie, Pennsylvania for the installation of its electrical components.
Twelve traction motors, two on each of the GG1's six powered axles, produced 4,620 horsepower (3,450 kW) that was transmitted to the 57-inch (1,400 mm) driving wheels by a quill drive.
Unlike other GG1s, access steps were installed at each end of the locomotive to ease maintenance of the pantographs; the pantographs were mechanically linked to a safety plate that blocked access to the steps when the pantographs were raised.
The finished locomotive was 79 feet 6 inches (24.23 m) long and 16 feet (4.88 m) tall, with both of its pantographs lowered.

GG1 4899 was extensively tested against the R1 from August to November 1934; both locomotives were substituted on regular passenger service between New York City and Philadelphia.
Both locomotives were found to be capable of rapid acceleration with short-term power outputs of up to 10,000 horsepower (7,500 kW).
The GG1, however, did not exert as much lateral force on the rails as the R1, because it was articulated, which allowed for a smaller turning radius than the rigid R1.
The Pennsylvania chose the GG1 over the R1 and immediately ordered another 57 locomotives.
As the number scheme used by the Pennsylvania prevented the first locomotive in the class from being 4899, the R1 and GG1 prototypes, essentially, swapped numbers.
The Pennsylvania also enlisted the assistance of Raymond Loewy to refine the aesthetics of the GG1s.
Loewy recommended that all subsequent models of the class should have a welded body rather than the riveted body on the prototype.
This led to the nickname "Old Rivets" being given to 4800.
In 1933, the Pennsylvania Railroad decided to replace the P5, and instructed General Electric and Westinghouse to design an electric locomotive that was more powerful than the P5, capable of speeds of 100 miles per hour (161 km/h), have a lighter axle load and to be double-ended with a cab in the center of the carbody. Westinghouse designed the R1 #4800, and General Electric submitted the GG1, then numbered 4899.
The frames, running gear and riveted body for the prototype GG1 were built by Baldwin Locomotive Works. The partially built locomotive was then shipped to the General Electric factory in Erie, Pennsylvania for the installation of its electrical components. Twelve traction motors, two on each of the GG1's six powered axles, produced 4,620 horsepower (3,450 kW) that was transmitted to the 57-inch (1,400 mm) driving wheels by a quill drive. Unlike other GG1s, access steps were installed at each end of the locomotive to ease maintenance of the pantographs; the pantographs were mechanically linked to a safety plate that blocked access to the steps when the pantographs were raised. The finished locomotive was 79 feet 6 inches (24.23 m) long and 16 feet (4.88 m) tall, with both of its pantographs lowered.
GG1 4899 was extensively tested against the R1 from August to November 1934; both locomotives were substituted on regular passenger service between New York City and Philadelphia. Both locomotives were found to be capable of rapid acceleration with short-term power outputs of up to 10,000 horsepower (7,500 kW). The GG1, however, did not exert as much lateral force on the rails as the R1, because it was articulated, which allowed for a smaller turning radius than the rigid R1. The Pennsylvania chose the GG1 over the R1 and immediately ordered another 57 locomotives. As the number scheme used by the Pennsylvania prevented the first locomotive in the class from being 4899, the R1 and GG1 prototypes, essentially, swapped numbers. The Pennsylvania also enlisted the assistance of Raymond Loewy to refine the aesthetics of the GG1s. Loewy recommended that all subsequent models of the class should have a welded body rather than the riveted body on the prototype. This led to the nickname "Old Rivets" being given to 4800.
Pennsylvania Railroad 4800