[1] 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.

[6] Both locomotives were found to be capable of rapid acceleration with short-term power outputs of up to 10,000 horsepower (7,500 kW).

On January 28, 1935, 4800 inaugurated electric passenger service between Washington, D.C., and Philadelphia by pulling a charter train for railroad and government officials; 4800 set a speed record of 102 miles per hour (164 km/h) outside of Landover, Maryland on the return trip.

[10] 4800 remained in regular passenger service with the Pennsylvania, until it joined production GG1s 4801–4857 in the pool of 90-mile-per-hour (140 km/h) geared freight locomotives.

[11] It had its steam generator removed in June 1960,[12] about a year after hauling a National Railway Historical Society-charted excursion to commemorate its 25th birthday.

In 1976, Conrail gave 4800 a red, white and blue paint scheme to commemorate the United States Bicentennial.

4800 was eventually retired by Conrail in October 1979 after the locomotive's main transformer failed, which was deemed too expensive to repair.