The owners vote in the DH for a 3 year experiment
Houston owner Judge Roy Hofheinz votes along with the rest of the National League to allow the American League to conduct a three-year experiment using the Designated Hitter. It will be the first time since the A.L. was formed in 1901 that the two major leagues would have a different set of rules. The gimmick has survived ever since and is now used by National League teams when involved in interleague play.