Ken Griffey, Jr. hits his league-leading 56th homer of the season and 350th of his career, becoming the youngest player ever to reach the milestone

On September 25, 1998 — Ken Griffey, Jr. hits his league-leading 56th homer of the season and 350th of his career, becoming the youngest player ever to reach the milestone. The 28 year-old outfielder drives in five runs in the Mariners’ 15-4 rout of Texas, who still manages to cop their second consecutive American League West Division title thanks to an Anaheim loss to Kansas City.