On May 12, 1958, Willie Mays hits the first grand slam in the brief history of the San Francisco Giants. Mays also belts another home run in a 12-3 victory over the rival Los Angeles Dodgers. The Giants had moved to San Francisco prior to the 1958 season.
Baltimore Orioles slugger Jim Gentile becomes the first major leaguer to hit grand slams in consecutive innings
May 9, 1961