The automatic transmission by a long time! I've clipped this info from the attached site
http://www.motorera.com/history/hist10.htm
The first automatic was invented in 1904 by the Sturtevant brothers of Boston. It provided two forward speeds that were engaged and disengaged by the action of centrifugal weights without need for a foot-operated clutch. As engine speed increased, the weights swung out to engage bands -- first the low-gear band and then the high-gear band. The unit failed because the weights often flew apart.
The next significant attempt at an automatic transmission was by Reo in 1934. Called the Reo Self-Shifter, it was actually two transmissions connected in series. For ordinary driving, one unit upshifted itself automatically in relation to car speed through the engagement of a centrifugal multiple-disc clutch -- much the same idea used by the Sturtevants. The second transmission was shifted manually and was used only when a lower gear was needed.
In 1937, Oldsmobile came out with a four-speed semi-automatic transmission called the "Automatic Safety Transmission" (AST). The driver depressed the clutch pedal and shifted into reverse or into one of two forward ranges: Low or High. Once in Low, the transmission shifted automatically from first to second; when in High, it shifted from third to fourth. Changes within each range were automatic by way of oil pressure and two hydraulically operated planetary gearsets. The shift points were preset according to the vehicle's speed. This AST transmission, an $80 option, was installed on about 28,000 1938 Oldsmobiles. The "safety" aspect referred to the claim that the driver could keep focused on the road rather than be occupied shifting. The significance of the AST is that it was the forerunner of the GM Hydra-Matic transmission which Oldsmobile introduced in 1939 and made available on the 1940 models. In 1938 Buick introduced a five-speed semi-automatic transmission in the Special, but it was so prone to trouble that it was dropped the following year.
The Hydra-Matic consisted of three planetary gearsets that were operated hydraulically. A fluid coupling was used to connect the engine and transmission. Credit for perfecting the fluid coupling goes to Chrysler, which developed the concept in 1937. However, Chrysler did not make use of it until 1941, when the Chrysler Fluid Drive transmission was introduced. This was not an automatic unit, but a standard transmission with a fluid coupling, not a clutch.
By 1948, the automatic transmission had evolved into the hydraulic torque converter that we know today coupled to a planetary geartrain. The first to use the converter was Buick. In 1948 Buick offered the Dynaflow fully automatic transmission as a $244 option on the Roadmaster. Within three years, 85 percent of Buicks had the Dynaflow. The Dynaflow was the model for present-day automatic transmissions. Others soon followed with similar units -- Chevrolet Powerglide, Fordomatic and Merc-O-Matic in 1950; and the Chrysler M-6 Torque Converter Automatic in 1951.
