The first motorized traffic light in the United States, installed in Detroit in 1920, was manually operated by a police officer in an elevated booth who switched between red and green based on visual traffic assessment, but the system failed so completely that drivers began ignoring the signals entirely, forcing cities to realize that automated, predictable timing would be more effective than human judgment—a lesson that wouldn’t be fully embraced until electric timing mechanisms became reliable in the 1930s.
Car Fact #57 — August 12, 2026
