Prior to 1914, there had been several attempts to create automobile traffic signals similar to those used by railroads, but it was only after a four-way electric signal was installed in Cleveland, Ohio, that the modern traffic light system began to take root. The signal had only two colors, green and red, but the three-color version still in use today was not far off. What US city claims to be home to the oldest working traffic light in the country? Discuss
Source: The Free Dictionary