professional baseball player, considered one of the most powerful hitters in the history of the game. In 1998 he set a major league record for most home runs in a season (70), breaking Roger Maris (Maris, Roger)'s mark of 61. See Researcher's Note: Baseball's problematic single-season home run record.

As a senior in high school, McGwire attracted more attention with his pitching than with his swing. The Montreal Expos drafted him as a pitcher in 1981, but instead he attended the University of Southern California, where he moved to first base, a position he was to maintain in the majors. Selected by the Oakland Athletics in the 1984 draft, McGwire joined the major league club in 1987 and quickly displayed the strength that would become his trademark. His 49 home runs that year set a rookie record and helped earn him American League Rookie of the Year honours. In 1989 his .343 postseason batting average guided Oakland to the World Series championship. Injuries, however, soon plagued McGwire, and from 1993 to 1995 he missed 290 games. In 1996, after briefly contemplating retirement, he became only the 13th player to hit 50 home runs in a single season. Traded to the National League Cardinals the following year, he posted 58 homers and elected against free agency to stay with St. Louis.

Attempts to top Maris's 37-year-old single-season home run record dominated the 1998 season. McGwire and the Chicago Cubs' Sammy Sosa (Sosa, Sammy) thrilled fans with their home run derby, and midway through the year McGwire hit one of the longest homers of his career (545 feet 【166 metres】). On September 1 he broke Hack Wilson's 68-year-old National League record (56 home runs), and six days later he tied Maris's mark. On September 8 McGwire hit his shortest home run (341 feet) of the year to break the record. The following year he became the second player (Sosa was the first) to hit 60 home runs in two seasons. McGwire held the home run record for only a brief period; the record was broken by Barry Bonds (Bonds, Barry) on October 5, 2001. (Bonds hit 73 home runs that year.) McGwire announced his retirement from baseball after the 2001 season.