Billie Jean King recalls the meeting that launched the women's tennis tour 50 years ago

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A half-century later, Billie Jean King thinks back on the landmark gathering of female tennis players at a London hotel shortly before they competed at Wimbledon and acknowledges she wasn't sure how things would go that day.

"I had no idea. Absolute toss-up. Because you never really know. What I did know was that certain players didn't like what we were trying to do," King said in an interview with The Associated Press. "And I did know it had to happen that day. Had to."

Wednesday marks the 50th anniversary of the meeting on June 21, 1973, at the Gloucester Hotel—about a mile south of Hyde Park in the heart of the British capital—where King and nearly 60 other players agreed to form what today is known as the Women's Tennis Association or WTA. They paved the way for their sport, and women's sports in general, to grow.

A reunion at that same hotel on June 30 is planned, with King, a twice-inducted member of the International Tennis Hall of Fame and an equal rights advocate, along with a dozen or so other founding members of the WTA, such as Rosie Casals, Betty Stöve, Françoise Dürr and Ingrid Löfdahl-Bentzer.

What memory stands out the most for King from that historic occasion?

"Standing at that podium and telling them, ‘This is it. We have to do this. I'm not going to spend any more time on it if we don't make it happen now. But I know we're going to make it.' I said, ‘This is our moment of truth. It's probably the most important decision we're ever going to make for our sport. So let's get it right,'" King recounted, rapping her right palm on a table. "I kept saying, ‘We have to do this. We've got to be together.'"

It was the beginning of what King said she kept referring to at the time as a "union," but what her lawyer kept reminding her was more properly referred to as an "association," bringing all women's professional tennis players under one umbrella.

"It was difficult to get everybody to feel as if they could commit and not worry about being penalized. They looked upon us to lead them the right way—and we did," Casals said in a telephone interview. "We hoped we had done the job by convincing the women they had to be there. Some of them hemmed and hawed, but eventually they joined."

The group's name initially was the Women's International Tennis Association, but King jokes now that she insisted: "Let's not do more than three letters, please. I can't remember it if there are too many letters. Can we just do three?" Eventually, it was shortened.

Before what turned into a successful vote to move forward with the effort, King asked Stöve—a Dutch player who won 10 Grand Slam titles in women's or mixed doubles and later served three terms as WTA president—to block the conference room's exit.

"I had Betty back there. I said, ‘Don't let anybody out until we have an association,'" King said. "But nobody left. Not one person even got up. It was amazing. We had their attention."

King was elected president, Virginia Wade was chosen vice president, Lesley Hunt was assistant vice president, Dürr and Löfdahl Bentzer were co-secretaries, Stöve was treasurer, and Casals chaired a committee to examine the rankings system.

This was nearly three years after the Original 9 group of King, Casals and seven other female players—Peaches Bartkowicz, Judy Dalton, Julie Heldman, Kerry Melville Reid, Kristy Pigeon, Nancy Richey and Valerie Ziegenfuss—signed $1 contracts with World Tennis Magazine publisher Gladys Heldman on Sept. 23, 1970, to participate in the first women-only tennis tournament.

That set the stage for the Virginia Slims circuit and, eventually, the WTA.

"Probably the two happiest days of my life—my tennis life, not my real life—were the Original 9 and the WTA," said King, whose 39 Grand Slam trophies include 12 in singles. "To get people to change. To get people to be together. To get people to have one voice and have power."

A few years later, Chris Evert surpassed $1 million in career earnings, the first female athlete to do so. A decade later, Martina Navratilova made that in one season.

"To look back and to look forward and to see where women's tennis is today? I would love to play now," said Casals, who won eight Grand Slam titles in women's or mixed doubles and twice was the singles runner-up at the U.S. Open.

These days, the WTA has more than 50 tournaments at its top level, along with about 20 others on a lower tier and, including Grand Slam tournaments—which now all pay equal amounts to women and men—more than $180 million available in prize money each season.

"The sport is still not where we want it, but 50 years has just gone like that," King said, clapping her hands for emphasis. "I like the fact we've helped other sports, too, because we're teeing up a culture of women's sports. I know we started it. We're the ones. I don't know how long we'll be the leaders, but we're still the leaders."