As I understand it, professional wrestling was initially a legitimate sport. Up until around 1920, the matches were mostly competitive (though there was a healthy dose of match fixing even then.) These matches were being promoted and sanctioned by some independent sporting organization (I know there were athletic clubs in New York, LA, and Boston for example), as well as national groups like the National Boxing Association and it's spin-off National Wrestling Association.
By 1938 and the formation of the National Wrestling Alliance, the sport has become entirely worked (barring the occasional unplanned double-cross), with outcomes and title changes being predetermined and key parts of matches scripted ahead of time. These matches were promoted by privately owned regional wrestling promotions (under what was called the territory system.)
What I'm not really clear on is how that transition happened. When did it begin, and how did the promoters in the athletics organizations convince the wrestlers -- and each other -- to go along with the staged matches? Did this transition happen all at once, or was there a long stretch of time where some titles were being contended legitimately, while others were entirely predetermined?