Not very many television shows can claim that they have helped millions of children. But Sesame Street can. A study first written in 2015 but recently published in the American Economic Journal quantifies just how big a difference the show made, comparing the educational and professional achievements of children who had access to the show compared to those who didn’t.

In “Early Childhood Education by Television: Lessons from Sesame Street,” researchers Melissa Kearney and Phillip Levine measured whether children’s access to Sesame Street before they turned seven impacted their elementary school performance and long-term outcomes in education and the labor market. To do this, they relied on a quirk of federal broadcast licensing (paywall). When Sesame Street aired in 1969, about two-thirds of US households with TVs had access to it, thanks to a higher-quality television signal, while one-third didn’t, because they had a lower-quality signal. The researchers mapped out which counties had access to the two signals and then, using US Census data from 1980, 1990, and 2000, assessed kids from those counties based on three factors: what proportion of children were enrolled in the appropriate grade for their age; whether they attended college, dropped out of college, or graduated from college; and their employment, hourly wage, and poverty status.

Kearney and Levine assumed that kids who had access to the Sesame Street signal on their TVs watched it at some point. (It’s a fair assumption: During a six-week period in 1990, the Department of Education said that 63.3% (pdf) of all US households with a TV and at least one child under six years old watched the program.) As Kearney told the American Economic Association, the “advantage of this strategy is that whether or not you watched it didn’t have anything to do with how important it was to your parents that you learned or how interested you were as a kid in learning. It just has to do with this predetermined technological determination in your county at that time.”

Image: American Economic Journal

They found that access to the show was associated with improved elementary school performance in “the generation of children who experienced their preschool years when Sesame Street was introduced in areas with greater broadcast coverage.” In the 1980 Census cohort, for example, kids who had access to Sesame Street were “1.5 to 2 percentage points more likely to be at the grade level appropriate for their age.” The study also found that boys, kids who grew up in poor counties, and black children were particularly impacted by access to Sesame Street. However, the researchers found little to no effect on longer-term factors like college attendance and employment, save for “some small long-term labor market improvements.”

The study shows correlation, not causation—that is, it can’t prove that watching Sesame Street was the cause of improved performance in elementary school. And the data also suggested, but couldn’t prove conclusively, that the benefits associated with watching the show as a child faded by the time kids graduated high school. Still, Kearney says, the results suggest that Sesame Street had a “sizable” impact.

The Sesame Street model of early childhood education

Sesame Street was a product of the 1960s, an era when researchers and government officials were just beginning to understand that investing in little kids made sense from a social, political, and economic perspective. It was designed to help preschool kids, especially children from low-income backgrounds, learn the skills they would need to keep up in school.

The show was unique not just because it accomplished what it set out to do, but also because it did so in a cost-effective way. At its peak, Sesame Street was reaching a majority of US preschoolers. Remarkably, Kearney and Levine write, the show cost “around $5 per child per year (in today’s dollars).” For comparison, the federal government spends more than $7 billion a year on Head Start, another product of the 60’s—or about $7,600 per child per year. (The actual cost is probably higher, but donors and individual states often contribute.)

Levine says it would be difficult to replicate the Sesame Street model of early childhood education today. Kids have so many entertainment options that no single program could ever have the same reach. “It’s really, really hard to understate what a huge influence Sesame Street had on society,” he tells Quartz. ”It’s still a possibility that these sorts of interventions can have an impact. I think it’s harder, because there is more stimulus for children these days than in the 1960s. But it doesn’t mean that it’s impossible and that doesn’t mean it wouldn’t be effective.”

The success of the show holds some lessons for early childhood educators today, according to Levine. First, steep any program in the science of early childhood development and behavioral psychology; that’s what made Sesame Street so impactful. “There was nothing else at the time that competed with it in terms of trying to provide academic content,” he says.

Second, technology can help get this kind of high-quality educational message across to the right audience at scale: “What our study shows is that it is possible for forms of media to have a beneficial impact on a child’s life in terms of their early childhood development.”

That doesn’t mean that Sesame Street alone is the solution to all our social ills. The study came under fire when it was first written for its claim that “the introduction of Sesame Street for white and black, non-Hispanic children had similar effects on elementary school performance as did participation in the Head Start program.” James Heckman, a Nobel laureate and one of the world’s foremost experts on the economics of early childhood, told The Washington Post (paywall): “The solution for promoting school readiness and fostering productive skills isn’t simply planting children in front of the television or tablet. High-quality educational programming can serve as a complement to quality early childhood education, not as a replacement.” Kearney and Levine agree: As they wrote in The New Republic, “we do not believe that Sesame Street should substitute for preschool or other enriching activities.” “Rather,” they said, “we support the role that TV and technology more generally can play in assisting parents, caregivers, teachers, and policymakers to augment more traditional preschool interventions.”

But what has really set Sesame Street apart from other early childhood interventions is its ability to adapt to changing times and different cultures. The show hasn’t faded into irrelevance over the last 50 years: Versions of Sesame Street are present around the world, from South Africa to Germany to India (paywall). And Sesame Workshop (the nonprofit educational organization behind Sesame Street) is now active in refugee camps in Bangladesh and Jordan, where it is aims to use the power of play to help traumatized children. Not too shabby for a bunch of muppets.