Sept. 24, 1909,
Thomas M. Flaherty filed for a U.S. patent, with an idea for a "Signal for Crossings" This was the first U.S. application for a traffic signal design, later issued as No. 991,964 on 9 May 1911. His signal used a large horizontal arrow pivoted on a post, which turned to indicate the right of way direction. It could be activated by an electric solenoid by a policeman beside the road. Although filed first, it was not the first patent actually issued for a traffic signal. Ernest E. Sirrine filed a different design seven months after Flaherty, but his patent was issued earlier, and thus he held the first U.S. patent for a "Street Traffic System"
Now developed as the red, yellow and green, universally ignored “traffic light”.