(CNN) -- The year was 1972. "M*A*S*H," "Sanford and Son" and "Kung Fu" were reasons to stay home and watch TV. Roberta Flack had the number one song on the radio with "The First Time Ever I Saw Your Face." Don McLean drove his Chevy to the levee and sang goodbye to Miss "American Pie."
The women's liberation movement was in full swing, but in schools there were huge educational discrepancies between the genders, both in the kinds of classes they took and in the kinds of extracurricular activities they took part in.
That year, there were only 30,000 girls in the U.S. participating in high school sports.
Today there are more than 3 million.
Changes came about in large part because of a law known as Title IX.
When President Richard Nixon signed the bill into law on June 23, 1972, it was intended to level the playing field between girls and boys in the educational opportunities that were presented to them. Title IX of the Education Amendments Act of 1972 (http://www.pvamu.edu/Include/EEo/titleIXflyer108pdf.pdf) states:
"No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any education program or activity receiving federal financial assistance."
The law set out to prevent sex discrimination and harassment in any education activity or program, whether public or private. It covers a wide range of areas, including fairness in college admissions and financial aid, freedom to take any vocational courses (so boys can take what was once called "home ec" and girls can take wood shop) and providing education for pregnant students.
Yet Title IX is most associated with sports because of its impact on high school and college sports for young women. Under the law, "The athletic interests and abilities of male and female students must be equally and effectively accommodated."
From the beginning, there have been some commonly-held misconceptions about Title IX. The law does not require colleges and universities to offer specific sports nor the same number of sports for each sex. It does not say that the same amount of money must be spent on men's and women's sports at schools and colleges.
Four decades after its passage, there has been a dramatic increase in participation in school sports among young women -- 904% in high schools and 456% in college.
Though some maintain that Title IX is no longer needed, advocates say that because studies have shown long-term benefits of playing sports for young women, both in terms of health habits and lower teen pregnancy rates, as well as better grades and self-esteem, schools and colleges should offer young women more sports programs.
And since an athletic scholarship can be a student's only way to pay for college, there are economic benefits at stake as well. According to the MARGARET Fund of the National Women's Law Center, each year male athletes receive about $130 million more in college athletic scholarships than female athletes get.
Last year, tennis great and Women's Sports Foundation founder Billie Jean King said of Title IX, "We've got a long way to go; we're still not in compliance."
As Title IX celebrates its 40th anniversary, there will be another milestone for women in sports: This year, for the first time, an equal number of male and female athletes will compete in the Olympics.