The U.S. Open has been the most prestigious American tennis tournament for five decades although its roots date back more than 130 years. Serving as the last of the Grand Slam tournaments, the U.S. Open celebrates its 50th Anniversary today it’s worth revisiting how the competition evolved from an amateur event to the juggernaut it is today.

In The United States Tennis Association: Raising the Game (Nebraska, 2017), author Warren F. Kimball details the challenges the association faced as it opened the tournament to professionals. The opening of what was once the U.S. National Championship was the result of a long period of democratization of the US Tennis Association, with everything from the league promoting more junior-level play, the sports growing popularity outside of the northeastern United States contributing to the change.

This democratization ultimately came to a head due to increased tension between the old guard, who wanted to see an opportunity for talented amateurs to compete on the national stage and those who hoped for the Association to create a prestigious platform for American professionals to compete. The decision was made in 1967 to allow professionals to compete and once the door was open at the 1968 U.S. Open, the tournament and American tennis scene was forever changed.

According to Kimball, the U.S. Open quickly proved to be one of the biggest sources of growth for the United States Tennis Association. He writes that a 1985 report proved that the television rights for the tournament proved to be a massive source of revenue, saying:

The long-term financial gains for the USTA were enormous. The relationship with CBS lasted for forty-six years, increasing regularly until, in 2014, when the contract expired, the USTA was reportedly receiving $30 million per year with escalation provisions. The new arrangement with ESPN reportedly brings an annual payment of $75 million to the Association.”

The U.S. Open has continued to be one of the most visible tournaments in the world, drawing more than 5 million viewers from around the planet in its most recent years. This year’s tournament runs through September 9.