A truism that bears continual restating; the Edwardian / “progressive” era was really, truly racist. Even the most diehard bigots these days would be unlikely to begrudge a black man his boxing career, but it took the best part of a decade of being the best boxer in the world, and two years of stalking his opponent, before Jack Johnson was able to compete for (and win) the world heavyweight title from Canadian Tommy Burns.
This was not, of course, allowed to pass unnoticed. The next two years saw a host of competitors put up against Johnson as “the great white hope” until finally superstar world champion James J Jeffries was brought out of retirement to challenge Johnson in “the fight of the century” – the film of which was distributed across the USA. The viewing of Johnson’s victory sparked race riots, which led to a nationwide ban on the distribution of fight films. Nearly a hundred years later, it would be entered into the National Film Registry.
A decent podcast about Jack Johnson can be found at Stuff You Missed in History Class – usual provisos about excessive advertising apply.