In Atlanta, Georgia, trolleybuses, generally called trackless trolleys there, were a major component of the public transportation system in the middle decades of the 20th century, carrying some 80 percent of all transit riders during the period when the system was at its maximum size. At the end of 1949 Atlanta had a fleet of 453 trolleybuses, the largest in the United States, and it retained this distinction until 1952, when it was surpassed by Chicago.
As in many other cities, trolleybuses mostly took over streetcar routes. Some Atlanta streetcar lines were converted to buses starting in 1925. Those early conversions were to "motor buses" (gasoline-powered buses), but starting in 1937 some streetcar lines were converted instead to trolleybuses. The first trolleybus route opened on June 28, 1937, and was a suburban route to East Point and with branches beyond to College Park and Hapeville. A second route opened in 1940. Conversions continued until closure of the last streetcar line, in 1949.
In 1950, 453 trolleybuses served 31 routes. Trolleybuses made up 70% of the fleet, but carried 80% of the transit system's riders.
The transit system was owned and operated by the Georgia Power Company until June 1950, at which point it was sold to a group of local businessmen, who formed the Atlanta Transit Company (ATC). Trolleybus service continued, and the large network of electric routes remained largely intact for another decade. One of the system's unusual features was express operation, uncommon on trolleybus systems. Express service ultimately was implemented on eight routes, and these were equipped with 250-foot (76 m) long "sidings" in the overhead trolley wires to enable vehicles on express trips to pass those on "local" trips. Although the pace of expansion slowed after 1950, it did not cease. Extensions continued to be built under ATC, including the conversion of bus line 26-Perry Homes to trolleybuses in November 1956, and extensions of that route in 1960 and 1962. There were 39 trolleybus routes at the end of 1962.
In late 1962 Atlanta Transit decided to phase out all trolleybus service the next year, to avoid the expense of having to string new overhead wires when extending service to new areas. Another reason cited was the anticipated high cost and difficulty of obtaining new trolleybuses to replace ATC's large fleet, which ranged in age from 14 to 17 years. Since 1959, when Marmon-Herrington ceased production of trolleybuses, no manufacturer in North America was still making the electric vehicles (a situation which lasted until the late 1960s). At the beginning of 1963 the active fleet included 273 trolleybuses. The entire electric system was converted to diesel buses over a period of less than one month in September 1963. Atlanta's last trolleybus service operated on the night of September 27, 1963.