In 1973, strong cattle prices led to increased cattle thefts. To help identify rustlers, legislators suggested livestock trailers be identified by using a mandatory state license tag. To save money and provide an easier option, Oklahoma Farm Bureau members suggested that farmers, ranchers and owners of stock trailers be required to display their drivers license number on the back of their trailers, which also allowed highway patrolmen to check the driver without even stopping the vehicle. The idea was adopted at the OKFB convention in November 1973 and signed into law by Oklahoma Gov. Dan Hall in April 1974, less than six months later.