In 1995, the United States had only eight public schools for girls. When a new one was born the very next year, it was attacked by the National Organization for Women and the American Civil Liberties Union for unconstitutionally denying equality of the sexes.

That argument didn’t work. The country now has at least 90 public girls schools. I thought that was nice but unimportant until I looked at the latest results of my annual high school rating list. Some of those public girls schools are doing amazing things.

Six such campuses in Texas and one in Florida have become among the most challenging in the country, reaching the top third of 1 percent of all U.S. high schools measured by participation in college-level exams last year.

The Texas schools are the Young Women’s Leadership Academy in San Antonio, the Young Women’s Leadership Academy in Fort Worth, the Young Women’s College Preparatory Academy in Houston, the Margaret Talkington School for Young Women Leaders in Lubbock, the Irma Rangel Young Women’s Leadership Academy in Dallas and the Ann Richards School for Young Women Leaders in Austin. In Miami, the Young Women’s Preparatory Academy is ranked as high as the Texas schools.

What they have done, through hard work by students and teachers, marks a new stage in a long debate over whether single-sex schools are good for students and for American education.

When I became a full-time education writer in 1997, U.S. public schools that admitted just girls or just boys were hard to find. Some civil rights leaders said the few that existed were wrongly discriminating against the gender they did not admit and should follow the coed trend in higher education. My wife, for example, graduated from a women’s college long associated with my college, which was once all men. Her school eventually closed and mine took over, becoming a coed institution.

But in 1996, U.S. Supreme Court Justice Ruth Bader Ginsburg wrote an opinion noting that females and males, unlike blacks and whites, have “inherent differences.” So single-sex education in public schools was constitutional if districts made comparable courses, services and facilities available to both sexes. Sens. Hillary Clinton (D-N.Y.) and Kay Bailey Hutchison (R-Tex.) jointly added a provision to the 2002 No Child Left Behind Act that further encouraged single-sex education.

In 1996, Ann Tisch, wife of Loews Corp. co-chair Andrew Tisch, opened the Young Women’s Leadership School of East Harlem. She thought the all-girls format would reduce the rate of teen pregnancy among impoverished students like those she had interviewed when she was a national correspondent for NBC News. The network of similar schools she and her team created in New York City had that effect, but other factors also sparked the growth of such schools there and elsewhere.

Lee Posey, a successful Texas business executive whose mother had gotten no further than eighth grade, visited the East Harlem school and started a similar school in Dallas in 2004. It was named for Irma Rangel, a state legislator who had expanded educational opportunities for low-income children. It is now one of nine schools in the Young Women’s Preparatory Network in Texas, with one in Austin named after former Texas governor Ann Richards and one in Lubbock named after philanthropist Margaret Talkington.

The six Texas schools I named above did well on my 2020 Challenge Index list. They ranked 28th (San Antonio), 32nd (Fort Worth), 39th (Houston), 56th (Lubbock), 60th (Dallas) and 78th (Austin) in the country. The Young Women’s Preparatory Academy in Miami ranked 38th.

Berta Fogerson, chief academic and accountability officer of the Texas network, said its schools are all partnerships with their local districts. Preparation for college-level Advanced Placement classes begins in sixth grade. Some students enroll in AP classes as early as ninth grade.

“The experience of sitting through an AP course is in and of itself a college preparatory experience, whether or not a 3 or higher is earned on the AP exam,” Fogerson said. “We find that even those who do not earn a qualifying score are more apt to be successful when they take the class in college, simply because of the rigor of the work.”

The Miami school and the nine schools in the Texas network all start in sixth grade. Cecilia Reverte, the AP coordinator at the Miami school, said, “I believe the secret of our success is our high expectation combined with a lot of support for both students and staff.”

Six of the seven public girls schools on my list have more than 50 percent of students from low-income families. The Lubbock school is 46 percent. The highest is the Houston school at 96 percent. Often schools with that many impoverished students have relatively low passing rates on the AP exams. But all seven schools have at least 60 percent of their seniors passing at least one AP exam, three times the national average. Four of them are above 80 percent.

Public girls schools, if well managed, have been shown to increase achievement, particularly in math and science, but critics argue that their students would have done just as well in coed schools. Leonard Sax, a psychologist and physician who has been a leading proponent of single-sex schools, said that “just offering an all-girls school accomplishes nothing good by itself, if teachers do not have evidence-based training in how to take advantage of the all-girls format.”

Other research suggests boys are improving in school but girls are doing better. My own sense is that high schools on average don’t have high expectations for either gender. The Young Women’s schools show how to change that. Their methods have proved good for boys, too, no matter what kind of schools they are attending.