Over the last four decades, the financial circumstances into which children have been born have increasingly determined where they have ended up as adults. But an expansive new study, based on billions of social media
These cross-class friendships — what the researchers called economic connectedness — had a stronger impact than school quality, family structure, job availability or a community's racial composition. The people you know, the study suggests, open up opportunities, and the growing class divide in the United States closes them off.
"Growing up in a community connected across class lines improves kids' outcomes and gives them a better shot at rising out of poverty," said Raj Chetty, an economist at Harvard University and the director of Opportunity Insights, which studies the roots of inequality and the contributors to economic mobility. He was one of the study's four principal authors, with Johannes Stroebel and Theresa Kuchler of New York University and Matthew O. Jackson of Stanford University and the Santa Fe Institute.
The findings show the limitations of many attempts to increase diversity — such as school busing, multifamily zoning and affirmative action. Bringing people together is not enough on its own to increase opportunity, the study suggests. Whether they form relationships matters just as much.
"People interested in creating economic connectedness should equally focus on getting people with different incomes to interact," Stroebel said.
Jimarielle Bowie grew up in a lower-middle-class family. Her parents divorced, lost jobs and lost homes. So when she made friends in high school with girls who lived on the rich side of town, their lifestyles intrigued her. Their houses were bigger; they ate different foods; and their parents — doctors, lawyers and pastors — had different goals and plans for their children, including applying for college.
"My mum really instilled working hard in us — being knowledgeable about our family history, you have to be better, you have to do better," said Bowie, 24, who goes by Mari. "But I didn't know anything about the SAT, and my friends' parents signed up for this class, so I thought I should do that. I had friends' parents look at my personal statements."
Bowie became the first person in her family to get a postgraduate degree. She's now a criminal defence lawyer — a job she found through a friend of one of those high school friends.
"My experience meeting people who were more affluent, I got to get in those circles, understand how those people think," she said. "I absolutely think it made a significant difference."
Birds of a feather
Social capital, the network of people's relationships and how they are influenced by them, has long intrigued social scientists. The first known use of the phrase was in 1916, by L.J. Hanifan, a school administrator in West Virginia. Since then, researchers have found that ties to more educated or affluent people, starting in childhood, can shape aspirations, college-going and career paths.
But the new study — using a significantly larger data set than other studies, covering 21 billion Facebook friendships — is the first to show that living in a place that fosters these connections causes better economic outcomes.
The researchers limited the data, which did not include names, to active Facebook users. They estimated users' incomes based on their ZIP codes, college, phone model, age and other characteristics.
For each low-income Facebook user, the researchers determined where the person was currently living, and how many high-income friends they had. That gave them a measure of how economically connected each neighbourhood was. Then they compared the new data with earlier research that used tax records to measure how much a particular neighbourhood raised low-income children's economic prospects.
The researchers were also able to link almost 20 million users to both their high school and to their parents on Facebook. Using those ties, they repeated their analysis, this time on high school connections between children of rich and poor parents, to measure the effect of relationships made early in life. They did a similar analysis for teenage Instagram users. And they built on an earlier analysis of siblings who moved at different ages to show that it was the place that made a difference, versus something about the families who moved to those places.
Each analysis had the same result: The more connections between the rich and poor, the better the neighbourhood was at lifting children from poverty. After accounting for these connections, other characteristics that the researchers analysed — including the neighbourhood's racial composition, poverty level and school quality — mattered less for upward mobility, or not at all.
"It's a big deal because I think what we lack in America today, and what's been dropping catastrophically over the last 50 years, is what I call 'bridging social capital' — informal ties that lead us to people who are unlike us," said Robert Putnam, the political scientist at Harvard who wrote Bowling Alone and Our Kids, about the decline of social capital in the United States. "And it's a really big deal because it provides a number of avenues or clues by which we might begin to move this country in a better direction."
Other kinds of social capital matter, too, like rates of volunteering in a community and friendships with people from similar backgrounds. Yet the new study shows that even in places lacking in other kinds of social capital, an increase in cross-class relationships is enough to benefit children's economic prospects. And it's this kind of social capital that has decreased as the country has become more segregated by class. In recent decades, people have become more likely to live in neighbourhoods and attend schools with people of similar economic status — behaviour that social scientists say is driven by anxiety about falling down the income ladder in an age of growing inequality.
"The pressure that parents feel to try to give their kids a competitive advantage is amplified when society is unequal and there's more to be lost," said Jessica Calarco, a sociologist at Indiana University who studies inequality in schools and among families. "Our society is structured in ways that discourage these kinds of cross-class friendships from happening, and many parents, often white, are making choices about where to live and what extracurriculars to put their kids into that make those connections less likely to happen."
As a result, rich people have mostly rich friends, and poor people have mostly poor friends.
Low-income people are far more likely than high-income people to make friends in their neighbourhoods, the study found. But in poorer areas, there are fewer rich people nearby to befriend.
It's human nature to befriend people who are similar, which is why most cultures have a phrase like "birds of a feather flock together," Putnam said. Even when people do form cross-class connections, there is evidence in this and other research that they gravitate toward people of the same race.
Bowie, who is Black and Japanese, said the friends she made from wealthier families were also Black.
"Just being with Black people who had money was a culture shock," she said. "But white people with money had a completely different lifestyle. At least with Black people, we had the same sayings, we saw the same movies, our grandparents had the same beliefs."
The analysis did not directly measure the role of race, which was not provided in the Facebook data. (Although there are techniques researchers use to guess race, the authors of the new study did not use them.) But in more racially diverse places, the study found fewer cross-class relationships.
Race is clearly associated with levels of mobility, a variety of research has shown, including by Chetty's team. In general, Black people in segregated areas are more likely to experience concentrated poverty and have worse economic outcomes.
"There was speculation that maybe it was about differences in resources, quality of schools, social norms," he said. "What we show here is places that have large Black populations tend to be more economically disconnected — both Black and white people living there have fewer high-income friends."
It's clear that other factors also influence outcomes for Black people in both segregated and integrated areas, he said, including racial discrimination in the labour market and mass incarceration.
But the researchers say their findings on the importance of cross-class relationships are true regardless of race. They found the same relationship — high economic connectedness leading to higher economic mobility — in neighbourhoods that were nearly entirely white, Black or Hispanic.
'A culture of success'
The researchers focused on high schools, one of the few settings where people of all classes make friends at similar rates, and a place where people form lifelong friendships before they start making decisions that may determine their economic trajectories.
Angelo Rodriguez High School in Fairfield, California, which Bowie attended, had more cross-class friendships than the average large public high school.
Fairfield, midway between Sacramento and San Francisco, is an unusually diverse area, racially and economically, and three-quarters of Rodriguez High's student body of around 2,000 are students of colour. The school, which opened in 2001, had a catchment area shaped like a reverse C, drawing from neighbourhoods on the far sides of town — which is how Bowie ended up commuting to a wealthier area for school. It also allows some students outside the boundary to attend.
In general, larger and more diverse schools — both economically and racially — have a smaller share of cross-class connections. It can be harder to make friends in large groups, and there are more chances to form cliques with people from similar backgrounds. But Rodriguez High nurtured cross-class friendships in ways both planned and unintentional.
"Being at Rod, you become friends with everybody," Bowie said. "Literally that's what that school does."
One thing that may have helped was the school's campus layout, with a promenade around a central library, outdoor stage and quad. That was deliberate, said John Diffenderfer, president of Aedis Architects, which designed the campus: "Accidental unstructured interactions between students was a very high priority."
Rodriguez High has a block schedule in which classes meet for two hours each, every other day. This creates small, diverse groups that spend a lot of time together. When large institutions do this, it helps foster cross-class friendships, the research found. Separating students based on academic achievement, through gifted or international baccalaureate programmes, has the opposite effect.
Extracurricular activities and interest clubs also play a big role in bringing together students from different backgrounds, said Catie Coniconde, a Rodriguez school counsellor who also graduated from the school, in 2006. Half the student body is enrolled in them.
"Kids get identified by their extracurriculars, more than race or socioeconomic status," she said. "There's the athletes, the band kids, the kids who are interested in anime."
Timothy Malacarne, a sociologist at Nevada State College, has found that the arts in particular seem to foster friendships across racial and economic lines. "Anytime people do something hard together, they're more likely to feel a sense of kinship that's not based on the identity of your racial or socioeconomic group," he said.
Athletics is another avenue, but sports are becoming more segregated as expensive club sports have overtaken recreational or school teams. Some school districts have begun offering free transportation, physical exams and equipment to allow more students to participate.
While pursuing shared extracurricular interests, the students begin to share aspirations, Coniconde said. Scoring well on the SAT and attending a four-year college are common goals at Rodriguez, she said. The students from the wealthier part of town usually arrive with those goals, while many students from lower-income families hadn't considered them before.
"It just seemed like a culture of success," she said. "The four-year push was huge at Rod, and it still is to this day."
The power of friends
These ideas can be applied beyond high schools, the researchers said.
Colleges, for instance, could place incoming students with small groups of roommates from a variety of backgrounds, instead of randomly assigning them roommates or allowing them to choose their own. Yale University does this, and the small groups generally live in the same dorms all four years. Its low-income students have unusually high levels of cross-class friendships. (It has fewer total such friendships, because low-income students are a minority, though it has committed to increasing the share to one-fifth by 2025.)
Large state colleges, where students can choose their roommates or sort into fraternities or sororities or off-campus housing, tend to have fewer friendships across class lines. The University of Mississippi, where more than one-third of undergraduates participate in Greek life, has one of the lowest rates of cross-class friendships of any large public university.
Cities could prioritise centrally located parks and other communal spaces, especially those that are free. Libraries could host radio studios, writing centres, cafes, maker spaces, tool libraries and other programming that appeals to wealthier residents while continuing to offer critical services to low-income residents, bringing both groups together in one physical space.
And mentorship programmes can build cross-class relationships, by pairing people from different socioeconomic backgrounds for extended periods. Friends of the Children matches at-risk children with paid professional mentors who spend four hours a week with them from kindergarten through high school graduation. Becoming a Man enrols boys in school-based counselling groups and matches them with young professionals as mentors. Both have been shown to have powerful effects on children's outcomes.
Bowie still lives in Fairfield and remains close with both sets of friends — those from her neighbourhood and those she met in high school. Their trajectories have differed. Most of her neighbourhood friends went to community college, live near home and are still figuring out what to do, she said. Her high school friends left town for four-year colleges and are pursuing careers in medicine and design.
Her experience straddling both worlds, she said, has been essential for her professional success.
"I got a lot of in-depth knowledge about cultures that I wouldn't have gotten, not in college, law school or now, because of my high school experience," she said. "Had I not had those experiences, I might have been really culture shocked by going into these spaces as an attorney."
Methodology: The data covered 72.2 million active Facebook users ages 25 to 44, keeping them anonymous. Active users were defined as those who had logged on in the last month and had at least 100 friends. The researchers ran the analysis using all of people's Facebook friends as well as only their 10 closest friends, and found very similar results. To verify that the data was representative of the overall US public in that age group, they compared their data set with census data. To verify that their estimates of socioeconomic status were correct, the researchers also used aggregated tax records and census data.
To calculate economic mobility for each ZIP code, researchers used anonymised tax data for people born from 1978 to 1983, which they had analyzed in previous research.
Opportunity Insights, the research group at Harvard run by Raj Chetty, has received a US$15 million grant from the Chan-Zuckerberg Initiative, run by Mark Zuckerberg and his wife, Priscilla Chan. Theresa Kuchler and Johannes Stroebel have had past research collaborations with Facebook; in 2018, they each received a US$135,000 unrestricted research gift from Facebook to NYU Stern, unrelated to the present research. Employees of Meta, Facebook's parent company, are listed as co-authors of the papers. The principal researchers said none of the funds from Meta or Facebook were used for this project, nor was Meta permitted to review or influence the findings, beyond ensuring data privacy. The research was funded by the Bill and Melinda Gates Foundation, the Overdeck Family Foundation, Harvard and the National Science Foundation.
This article originally appeared in The New York Times.
Written by: Claire Cain Miller, Josh Katz, Francesca Paris and Aatish Bhatia
Photographs by: Marissa Leshnov
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