Not too long ago, day care centers were smeared as dens of satanic rituals and Soviet-style indoctrination. When President Richard Nixon vetoed the creation of a national network of child care centers in the 1970s, he argued that they would “commit the vast moral authority of the National Government to the side of communal approaches to child rearing over against the family-centered approach.”

Then the 1980s came packed with news coverage of day care providers who supposedly molested children in their care and even involved them in animal sacrifice and witchcraft. Today the fearmongering has faded away and the issue of child care has become bipartisan, with everyone from Bernie Sanders to Ivanka Trump talking about the struggle parents of young children face when they try to secure care for their children in order to work or continue their education.

Yet little has actually changed for most of today’s working parents. Only a third of the country’s young children attend a preschool, and most of them go to private centers that can come with exorbitant price tags for parents. The nation’s capital, however, took one of the boldest steps yet toward providing affordable, quality care to parents with young children in 2009 when it began offering free preschool to all 3- and 4-year-olds who live in the District.

High-quality preschools can provide structure and help children’s development and social skills. But a lot less attention has been paid to what happens to parents when they have an affordable, safe place to send their kids every day. The full-day, free, universal preschool program in Washington, DC, had a huge impact on the employment of mothers with young children according to new research shared exclusively with Vox by the Center for American Progress (CAP), a progressive think tank. It offers evidence that government investment in providing early childhood education doesn’t just benefit kids, but also women, and potentially, the economy at large.

Providing child care for mothers who want to work could have some economic impact

The study, authored by CAP senior policy analyst Rasheed Malik, found that after the city implemented its universal preschool program, the share of mothers with children under the age of 5 who participated in the labor force — who were either employed or actively looking for work — increased about 12 percentage points, to 76.4 percent. Ten percentage points can be attributed to the preschool program.

That is a huge increase from one single policy change. These mothers now participate in the city’s labor force at about the same rate as mothers of kids in elementary school.

Preschool also appears to have increased how much women worked. The share of mothers with young kids who were employed rose from 56 percent to 67 percent; the share of married women with full-time work increased, as did the share of unmarried women with part-time work.

“When I started looking at the rates of moms with young children going into the workforce … it’s really stark,” Malik told Vox. “It [was] just chugging along at a pretty flat level, and then it just immediately shoots up. It’s the sort of thing where you’re like, ‘This is too good to be true or too big to be real.’”

These results are not just significant because they suggest that free quality care in kids’ early years could help working parents. They also provide a clue as to why women’s labor force participation in the United States has been falling since the early 2000s, lagging behind many other developed countries. The federal government invests a paltry amount in early childhood education compared to its peers: In 2013 it ranked 21st out of 36 developed countries in how much it spends on early childhood education.

“These results suggest that two years of universal, full-day preschool is associated with a large, positive effect on maternal labor supply,” the paper states. “Providing full-day, year-round child care for working parents will benefit millions of families, increase the lifetime earnings and savings of women, and bring women’s labor force participation into line with those of other advanced economies.”

It also affects overall economic growth. From the 1970s to the 2000s, a rise in women (many of them mothers) entering the workforce increased GDP by 11 percent. But the increase started flatlining and then declining in the early 2000s. One likely reason is how little structure exists to support working parents.

Enticing mothers to return to work with subsidized child care could potentially reverse the trend and, therefore, and increase GDP. The process, though, wouldn’t be cheap — an estimate by the National Academies of Sciences, Engineering, and Medicine of providing all children younger than Kindergarten age with high-quality care came to $140 billion a year, including $53 billion footed by the government itself. But, Malik argues, “I think that an investment in high-quality child care would pay for itself several times over in terms of overall economic growth nationwide.”

He added, “In very simple terms, economic growth is about how many people are able to participate in the labor force and how productive they can be. This clearly shows that investing in child care is going to increase labor force participation.”

CAP’s findings have other potential ramifications, too. The gender wage gap between men and women workers is in large part due to the impact having children has on women’s careers but not men’s. If the availability of preschool allows mothers to stay in the workforce, it could help erase that gap. “It tends to be Mom who is on the margin of being in or out of the labor force,” Malik noted. So investing in child care and preschool is “an investment in the choices that moms are able to make about whether they’re going to work or look for work.”

“If you want to think about gender equality, this is one thing you should think about,” noted Randy Albelda, an economist at the University of Massachusetts Boston.

The current landscape of child care in the US is a tough game for working parents

In most places around the country, day care for 4-year-olds costs parents more than $8,000 a year, on average, while private care in DC costs over $18,000 a year. And that’s if they can even find an open slot. Other CAP research has found that 42 percent of children under age 5 live somewhere that either has no child care centers or three times as many kids for each available opening. Most states earn a D or failing grade for their child care health and safety standards.

That’s what makes DC’s program so unique. It offers all parents who live within the district’s limits two years of free, full-day preschool, funded through the city’s general education fund. As of last year, about 90 percent of the city’s 4-year-olds and 70 percent of its 3-year-olds were enrolled. The program is also funded at levels similar to what the city spends on K-12 education, including comparable salaries for early childhood teachers, and meets research-based quality standards. It is, as the paper states, “one of the most robust, high-quality preschool programs.”

There’s the question, of course, of what DC parents do before their children turn 3. Child care for infants is even more expensive than for toddlers given that it requires more providers in the room and more hands-on care. The city council has started to consider that question, approving a bill to expand its current child care subsidy program to all children ages zero to 3 and put a cap on how much families spend out of pocket.

Other cities have also experimented with these policies. New York City rolled out universal preschool for 4-year-olds in 2014 and is now expanding it to 3-year-olds. Chicago Mayor Rahm Emanuel announced the city would do the same earlier this year, although he is now no longer running for reelection.

There’s been less action in the federal government, even if the issue has more bipartisan support these days. Democratic Sen. Patty Murray of Washington state and her colleagues introduced a bill last fall that would offer states money to implement universal pre-K and increase child care subsidies, while the Congressional Progressive Caucus’s budget calls for child care for all.

Republicans have also waded into the issue: President Donald Trump put forward a plan to address the cost of care on the campaign trail, while both Sens. Marco Rubio (R-FL) and Rand Paul (R-KY) have advocated for expanding tax breaks to help parents cover the price. Still, the country is a long way from providing free, high-quality care to all children, despite the evidence that it could offer enormous benefits.

“It reduces poverty, presuming it’s quality care it’s really good for kid’s education, it’s good for families, it improves gender equality, it will increase economic growth,” Albelda pointed out. “How many different ways can we study the benefits of early education and care before we have the political will to fund it?”