On May 18, 1999 — Luis Gonzalez of the Arizona Diamondbacks extends his hitting streak to 30 games with a two-run, 1st-inning home run in a 7 – 3 victory over the San Francisco Giants. Gonzalez, whose streak matches the longest this decade, becomes the 37th player in major league history to reach the 30 mark.
Source:
Baseball Reference May 18