Jimmie Foxx, 58, 1932
"Double X" homered four times in the first five games of 1932, his age-24 season, and after a nine-game drought, added 13 in May and 12 apiece in June and July. He hit his 40th in the A's 96th game, putting him on a pace for 64, well ahead of Babe Ruth's 1927 pace; the Bambino didn't hit his 40th until the Yankees' 120th game. Foxx hit just seven in August, but still closed the month ahead of Ruth (48 homers in 131 games compared to the Babe's 43 in 127 games). But a slow spell—four homers in the first 15 games of September—cost him crucial ground, and even with six homers in the final eight games, he fell short of the record, though he's still the youngest player to hit more than 52 in a season.