101 years ago today, Garrett Morgan from Cleveland, Ohio was granted a patent for his three-position light signal. It wasn’t the first traffic signal (one had been installed outside the Houses of Parliament in London in 1868), but it was an important innovation. The problem with existing traffic signals was that they switched back and forth between “Stop” and “Go” with no interval between to give drivers time to appropriately react. After witnessing an accident between a horse and buggy and a car, Morgan knew there had to be a better way. So he designed a manually-operated traffic signal with arms that could be raised halfway to indicate caution – basically the precursor to the yellow light today. Morgan later sold the rights to General Electric for $40,000.