This was on Wikipedia or whatewer it's called...it was way easier before 1963 to keep track of things...
In the first part of the 20th century, the United States became the centre for professional boxing. It was generally accepted that the "world champions" were those listed by the Police Gazette. After 1920, the National Boxing Association (N.B.A.) and the New York State Athletic Commission (N.Y.S.A.C.) began to sanction "title-fights". The N.B.A. was renamed in 1962 and became the World Boxing Association (W.B.A.). The following year, a rival body, the World Boxing Council (W.B.C.), was formed. The influence, internationally, of the N.Y.S.A.C. declined. In 1983, another world body, the International Boxing Federation (I.B.F.) was formed, and in 1989, this was followed by yet another, the World Boxing Organisation (W.B.O.). Each body sanctions its own title-fights and recognizes its own "champions". By the end of the 20th century, a boxer had to be recognized by four separate bodies to be the "undisputed champion" of the world, and each year saw over 100 "title-fights" take place in up to seventeen weight divisions.