Longest reigning boxing world champion

The Joe Louis heavyweight duration record of 11 yr 252 days stands for all divisions. Due to the numerous Boxing Associations (As of 2014, there are 5 with about 17 divisions in each!) that exist these can vary but very generally speaking the present boxing divisions are
Minimumweight - 105 lb /7 st 7 lb
Light Flyweight - 108 lb /7 st10 lb
Flyweight - 112 lb /8 st
Super Flyweight - 115 lb /8 st 3 lb
Bantamweight - 118 lb /8 st 6 lb
Super Bantamweight - 122 lb /8 st 10 lb
Featherweight - 126 lb /9 st
Super Featherweight - 130 lb /9 st 4 lb
Lightweight - 135 lb /9 st 9 lb
Light Welterweight - 140 lb /10 st
Welterweight - 147 lb /10 st 7 lb
Light Middleweight - 154 lb /11 st
Middleweight - 160 lb /11 st 6 lb
Super Middleweight - 168 lb /12 st
Light Heavyweight - 175 lb /12 st 7 lb
Cruiserweight - 200 lb /14 st 4 lb
Heavyweight - Over 200 lb /14 st 4lb
Joe Louis's reign started on 22 June 1937, when he knocked out James Joseph Braddock (USA) in the eighth round at Chicago, Illinois, USA, until announcing his retirement on 1 March 1949. During his reign Louis made a record 25 defences of his title.