Since the practice of female genital mutilation was outlawed by the United States in 1996, the federal-level crackdown has been swift and unforgiving. In the following decades, 22 states would add their own bans, and “vacation cutting,” or taking minors abroad for the purpose of FGM, would be outlawed. But now, new numbers show that these measures have done little to stanch the skyrocketing rate at which girls are subjected to this cruel form of circumcision on our shores.

Data has been slow to come to the aid of American activists against FGM. It’s been 25 years since the government released its first solid numbers on how many women may be subjected to the practice of genital mutilation in America. In 1997, the CDC estimated that 168,000 girls and women were at risk or had undergone FGM—at the time of the last national census in 1990. A few years later, in 2000, the African Women’s Center upped the number at 227,000.

But according to estimates released on Friday, there currently are around 507,000 girls living in the U.S. who are either at risk of being cut or who have already been cut. That’s more than triple the figure from the very first nationwide count.

This fresh data comes from a new report issued Friday by the nonprofit Population Reference Bureau, a Washington, D.C.-based nonprofit. It was culled from the U.S. Census’ 2013 American Community Survey. The PRB then crunched the numbers from immigration communities and compared them with the prevalence of FGM in the countries where those people hail from. Working under the assumption that first- or second-generation Americans either have experienced FGM or will at the same rate as their homeland counterparts, the PRB narrowed the focus to teens from 15 to 19, presumably most at risk, and women up to 49, a percentage of whom already have undergone the procedure. New York City and Washington, D.C. have the highest concentration, with more than 50,000 girls at risk in each city. Minneapolis, with its large Somali population, is third.

If this data seems ambiguous—“may have undergone” or “at risk of undergoing”—that’s because it is. Getting solid numbers on how frequently FGM is actually practiced in the U.S. has been virtually impossible. There is little information on what actually goes on in these insular immigrant communities, and with felony charges facing anyone who admits to orchestrating the cutting, it seems unlikely that many people would answer surveys truthfully.

The CDC was set to release a report of its own on Friday—the 12th annual International Day of Zero Tolerance to FGM—but at the last minute delayed the publishing indefinitely, saying the numbers were not yet finalized. According to The Guardian, the PRB figure is corroborated almost exactly in the draft of the CDC’s report.

The people most in the know—local teachers and healthcare providers—must be involved to paint an accurate picture of FGM in the United States. They’re also the ones with the best footing to stanch the practice.

Charlotte Feldman-Jacobs, the PRB’s program director for gender, says there’s a drought of good numbers. “How can we get better data?” she asks. “We need to find out more about where they come from because if you look at maps on FGM, it’s not from all parts of all countries. If you take, for instance, the north of a particular country, it may have a100 percent FGM rate, while another region of the same country has zero. So assuming a girl [from that country] has 100 percent been cut may be incorrect.”

This is why activists are pushing government agencies to create a bottom-up approach to information gathering, so that the federal level can better evaluate on-the-ground needs.

Sharing these numbers with residents of these immigrant communities also could be a first step to quashing the practice. The communities may not even be aware that the practice in many of their home countries actually is on the decline, says Feldman-Jacobs. From Benin to Iraq, from Liberia to the Central African Republic, the rate of FGM has dropped by as much as half among young girls in the past 20 years.

In Washington, the wheels are being set in motion. On Wednesday, two Democratic representatives, New York’s Joe Crowley and Sheila Jackson Lee of Texas, announced new legislation that will force the government to create a strategy to protect girls in America from FGM. They’re calling for a national study that would gather data on the practice, along with a cross-sector strategy to address it, pulling the expertise of teachers, healthcare workers, and law enforcement. Crowley, who previously authored a law criminalizing the travel of a minor out of the U.S. to undergo FGM, called for better data about the issue in a statement. “In order to improve efforts to protect these little girls, we must know the facts about FGM in the United States,” he said.

Part of the impetus behind the federal effort is a 25-year-old activist named Jaha Dukureh, who, along with advocacy group Equality Now, filed a petition last May asking the government to carry out a new study. Her story, as it was told to me at the time, and an examination of the underground FGM crisis in America, can be found here.