By 1923, traffic congestion from cars was strangling the business districts of many U.S. cities. In most downtowns, police had adopted a system of lights switched by hand, in the belief that motorists would not obey a signal if there wasn't a policeman present. Cleveland businessman and inventor Garrett Morgan improved on those ideas with a three-position "semaphore" type light that offered a warning similar to what yellow lights do today, or could be set in a caution mode when unattended. His key innovation wasn't the yellow light, but the system's automation; not only were timed lights better at handling traffic, they couldn't discriminate against black motorists — like Morgan himself.
- Garrett Morris
- traffic congestion