Who invented the yield sign?

Clinton Riggs, an Oklahoma Highway Patrolman, got the idea for a yield sign while attending a traffic institute meeting in 1939 at Chicago. The war years slowed its development but in 1959 the first yield sign was used at a dangerous intersection in Tulsa. It lowered the number of

accidents.

Soon the Keystone-shaped yield sign became popular and was adopted by cities and states across the nation. Riggs, who also had a successful career with the Tulsa Police Department, is credited with designing the Tulsa police shoulder patch in the same shape as the yield sign.