on wat date was the first traffic light in use?/?

Answer 1

The first automobile traffic light was invented around 1912 by Lester Farnsworth Wire,
who was then head of the traffic division of the Salt Lake City Police Department. His
two lamps, one red and one green, came from lights then in use on seagoing vessels
and railroad signals where they meant stop and go as they do now. This light was a large
wooden box with two six-inch holes on each side. Inside the holes were Mazda lamps which
had been dipped in red or green watercolors. The box was painted yellow and planted on top
of a ten-foot pole. The light was installed in Salt Lake City in 1912 at the intersection of Main
Street and Second South. It was operated by a patrolman who used a two way throw
switch to change the light’s colors. To power the light, wires from the box were
attached to the overhead trolley wires.

Answer 2

There is more than one correct answer for this question - this excerpt from wikipedia explains:

On 10 December 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J.P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January 1869, injuring the policeman who was operating it.

On Potsdamer Platz, Berlin Germany, it is widely claimed (though this is subject to some disagreement), that the world's first electric street lights were installed there in 1882. What is not refuted is that Europe's first traffic lights were erected there in 1924 in an attempt to control the sheer volume of traffic passing through. These lights were mounted on a five-sided 8.5 metre high tower, at the top of which a policeman sat in a small cabin and switched the lights manually, though they were automated after a few years (a replica of this tower was erected in the late 1990s close to its original location).

The modern electric traffic light is an American invention.[4] As early as 1912 in Salt Lake City, Utah, policeman Lester Wire set up the first red-green electric traffic lights. On 5 August 1914, the American Traffic Signal Company installed a traffic signal system on the corner of 105th Street and Euclid Avenue in Cleveland, Ohio. Based on the design of James Hoge, it had two colors, red and green, and a buzzer to provide a warning for color changes. The first four-way, three-color traffic light was created by police officer William Potts in Detroit in 1920.[1] In 1923, Garrett Morgan patented a traffic signal device, although it did not directly impact the evolution of the modern traffic light [5].

The first interconnected traffic signal system was installed in Salt Lake City in 1917, with six connected intersections controlled simultaneously from a manual switch. Automatic control of interconnected traffic lights was introduced March 1922 in Houston, Texas [6]. The first automatic experimental traffic lights in England were deployed in Wolverhampton in 1927. [7]

The first automated traffic light was introduced in Toronto, Ontario, Canada in the 1950s.[citation needed]Ampelmännchen pedestrian traffic signals have come to be seen as a nostalgic sign for the former German Democratic Republic.

http://en.wikipedia.org/wiki/Traffic_light#History

Good Luck!!!

Answer 3

It was 1920 in Detroit according to this link:
http://www.ideafinder.com/history/inventions/trafficlight.htm