Batter Team Age Year HR Reign Record breaker George Hall Philadelphia Athletics 27 1876 5 3 years -- Charley Jones Boston Red Caps 29 1879 9 4 years 6th on July 31 off George Bradley Harry Stovey Philadelphia Athletics 27 1883 14 1 year 10th on August 1 off Jack Neagle Ned Williamson Chicago White Stockings 27 1884 27 35 years 15th on July 9 off Ed Bagley Babe Ruth Boston Red Sox 24 1919 29 1 year 28th on September 24 off Bob Shawkey Babe Ruth New York Yankees 25 1920 54 1 year 30th on July 19 off Dickie Kerr Babe Ruth New York Yankees 26 1921 59 6 years 55th on September 15 off Bill Bayne Babe Ruth New York Yankees 32 1927 60 34 years 60th on September 30 off Tom Zachary Roger Maris New York Yankees 27 1961 61 37 years 61st on October 1 off Tracy Stallard Mark McGwire St. Louis Cardinals 35 1998 70 3 years 62nd on September 8 off Steve Trachsel Barry Bonds San Francisco Giants 36 73 17 years 71st on October 5 off Chan Ho Park
most major league home runs in a season
73