Mark McGwire, 70, 1998
McGwire's prodigious power had been on display since he set the rookie record of 49 in 1987, but when he finished the '97 season with 58—a number hindered in part by a three-week drought during which time he was traded from the A's to the Cardinals—the baseball world geared up for the long-awaited assault on Roger Maris's record of 61.
McGwire got No. 1 on Opening Day, March 31, and went deep in each of St. Louis's first four games. After going eight games without a homer—which would be matched but not passed as his longest drought of the year—he hit three on April 14 and had another three-homer game on May 19, putting him at 20 overall after just 41 games. He ended June with 37, four more than the Cubs' Sammy Sosa, who had hit a record 20 that month. The race was on.
On Aug. 20, McGwire homered in both games of a doubleheader against the Mets to reach 51, and hit a pair in each of the first two games of September to get to 59. He wasted little time making history. On Sept. 5 he caught Ruth with No. 60, tied Maris on Sept. 7 and the next day he hit a low line drive over the leftfield wall at Busch Stadium against the Cubs' Steve Trachsel for No. 62. The chase was over but the race wasn't. Sosa briefly pulled ahead in the season's final weeks but while he hit three in the final 10 games, McGwire crushed seven, including two each in the final two games of the season. He set the new mark at 70 with his final swing of the year on Sept. 27.
In 2010 McGwire admitted to using steroids, including during the 1998 season.