1920 : First Automatic Tri-Color Traffic Signal in Detroit

When:
December 20, 2021 all-day
2021-12-20T00:00:00-05:00
2021-12-21T00:00:00-05:00

On December 20, 1920, the first automatic tri-color traffic signal was installed in Detroit. Designed by Detroit Police officer William Potts, the new signal added the amber “caution” light & became the standard by the 1930s. You can learn more about it at

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