Bayh, who grew up on a farm in rural Indiana raising hogs, chickens and cattle, favors another barometer: Before the law was passed, less than 10 percent of the students in veterinary medicine schools were women. Today it's nearly 80 percent.
Judith Sweet, who pushed for better compliance with the law when she served as president of the National Collegiate Athletic Association (NCAA) in the 1990s, worries there's a downside to that progress. Sweet cites a recent email from a female student-athlete who said her teammates didn't know the law even existed.
"That's so common when we ask the question to young women: 'How many of you know about Title IX?'" Sweet said. "So many of them don't."
It doesn't bother Bayh quite as much to know there's a generation of athletes who take Title IX, and his role in its passage, for granted. "Maybe that's the way it should be," Bayh said. "Equal rights should be a given."
Knock-down, drag-out fight
"It was a long, hard path," is how Bayh describes the struggle for congressional approval.
Passage of Title IX was relatively easy. Equal access to education seemed less radical, Bayh said, than a companion cause he was championing at the time: a constitutional change to force gender equity through the Equal Rights Amendment.
Still, it took three years to get the regulations to enforce Title IX into final print, and signed into law by President Gerald Ford in 1975. And, in the meantime, the NCAA unleashed a massive lobbying effort to squash it. The organization's executive director, Walter Byers, warned his member schools of "impending doom around the corner" for popular male college sports if the law was enforced.