Some sources have credited Paul Rice with the invention.dead link Paul was a Tulsa city engineer who worked under Riggs, the Traffic Director of TPD. Riggs later told a Pittsburgh, PA interviewer that Paul had helped him erect some of the first signs in Tulsa, but later took credit for the invention in an article in Evanston, Indiana. Riggs' name was not even mentioned in the article. Riggs said he wrote Rice a letter complaining about his omission, but never received a reply. As late as 1989, Rice was still being credited with the invention in other news articles.