All-Star voting is returned to the fans, as computerized punch-card ballots appear in stores and ballparks coast to coast. Since 1958 the All-Star squads had been selected by managers, coaches, and players.

On May 30, 1970 — All-Star voting is returned to the fans, as computerized punch-card ballots appear in stores and ballparks coast to coast. Since 1958 the All-Star squads had been selected by managers, coaches, and players.

Source:
Baseball Reference May 30