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Where white people go, where Black people go: Cellphone data reveals how segregated Bostonians are in their movements

‘Stunning’ findings from a new atlas of American mobility.

Boston Globe Illustration; encierro/Adobe

We have long measured segregation — that great stain on the American experiment — by who lives where.

The Back Bay is mostly white; Grove Hall is mainly Black and brown.

But people don’t spend all their time in their own neighborhoods. They venture out for work or school or a doctor’s appointment. They ride across town for a job interview or a drink.

They move.

To understand segregation fully, we need to understand that movement. We need to know not just where people are from but where they go.

Until recently, it was difficult to track mobility at scale. But the cellphone location data that has transformed mapping, marketing, and media is opening up new possibilities in the social sciences too.


And academics are using billions of data points from millions of phones to construct a sprawling, dynamic atlas of American movement. A first-of-its-kind bird’s eye look at the living city.

The view is troubling.

The data shows our movements are heavily circumscribed by race — more heavily than we might imagine; color has such a powerful hold on where we go that it can trump class entirely.

And our mobility patterns are more than just a painful symbol of our disunion. They appear to have serious consequences for people of color.

They help explain the spread of COVID in Black and Latino neighborhoods. Even the spread of homicide.

And the segregation of our movements has more subtle effects, too. It can mean less access to celebrated cultural institutions for people of color. Less time in the finest city parks.

And less opportunity for the Black and brown strivers whose success may determine the fate of the country’s increasingly diverse cities.

Strivers like Shawn Burgess.

‘You just don’t go there’

Burgess grew up on Rockwell Street, just outside Codman Square in Dorchester. Trees shade the sidewalks, and chain-link fences surround two-family homes.


His mother was the dean of students at Roxbury Community College and his father owned an automotive shop.

The neighbors to the left and the right owned auto shops too.

Burgess made lifelong friends in the neighborhood, but there was an air of danger to the place.

Shawn Burgess poses at a home he is marketing in Dorchester on Oct. 22.Craig F. Walker/Globe Staff

It was the ’80s, height of the crack epidemic. Burgess remembers when the owners of Joseph’s Bakery, where he used to buy white cookies with sprinkles on top, painted the side of the building with the names of the young men from the area who had been slain.

It didn’t take long to fill the whole wall.

But this wasn’t the only world he knew. Burgess’s parents enrolled him in the Metropolitan Council for Educational Opportunity, or METCO, program, which sent a limited number of Boston students of color to suburban schools. Every day, he’d hop on the bus before light and get home after dark.

Race was always present at Cohasset High School, he says. Burgess remembers a classmate’s snide comment during a Black history discussion. And at lunch the METCO kids all sat together. But his suburban classmates were mostly kind to him. And he learned something important about navigating predominantly white institutions.

“By the time I got to college, it was really easy for me,” Burgess says. Unlike some other Black students at the University of Massachusetts Amherst, he knew what it was like to be the only one in a class.


And his experience helped him ease into a job with Blue Cross Blue Shield after college.

But even after spending so much time across the line in his formative years, Burgess’s foray into white America would prove provisional. As he grew older, he’d build a life in Black Boston. A life he chose. A life he prizes. But one limited, in some respects, by segregation.

Most of his peers would land in a similar place.

That’s evident in the work of Robert Sampson, a Harvard social scientist on the leading edge of the new mobility research.

Sampson has been an authority on the American city — what binds it together and what pulls it apart — for decades now.

As a young academic, he did influential work on neighborhood cohesion, measuring trust and cynicism and their effects on crime.

At one point, he worked with colleagues to slowly videotape 22,000 city blocks in Chicago in a bid to understand locals’ perceptions of order and disorder.

Now he’s focused on people’s movements in and out of the neighborhoods he’s studied so closely. And he says his findings suggest “that the nature of racial and class segregation is potentially greater than we think.”

For one paper, Sampson and his colleagues analyzed 650 million geocoded tweets from 400,000 people in America’s 50 largest cities.

The researchers used clusters of tweets to determine users’ home neighborhoods but, to preserve anonymity, didn’t pinpoint specific addresses. Then they examined where people from a given neighborhood went.


Not everyone uses Twitter, of course. But subsequent analyses of cellphone GPS data have closely matched findings from Twitter data, suggesting that the same travel patterns appear regardless of methodology — and remain quite stable over time.

Sampson and his co-authors found that while there is little difference in the number of places people from white, Black, and Latino neighborhoods visit, there are big differences in where they go.

And these racial differences are so powerful they can wipe out class considerations.

Data compiled for Ideas shows that someone from a poor white neighborhood in Boston is twice as likely as someone from a blue-collar or middle-class Black neighborhood to visit a better-off white neighborhood — including resource-rich places like the Seaport or Back Bay.

“I mean, that’s a pretty stunning statistic,” Sampson says.

And people from blue-collar and middle-class Black neighborhoods are no more likely to spend time in these white neighborhoods than people from poor Black neighborhoods. A similar pattern is found in Boston’s Latino communities.

This segregation of movement can have real repercussions for people like Burgess.

He’s in his old neighborhood these days. He built a house of his own on Rockwell Street. He rents office space for his real estate business from his pastor, right across the street from his father’s old repair shop. And he can walk to the majority of his listings.

Burgess says he loves helping people in Dorchester, Roxbury, and Mattapan buy homes, accumulate wealth, and build families. But he says his business has undoubtedly suffered for not stretching into the city’s whiter, wealthier precincts.


And he traces the limitations on his business back to the segregated mobility patterns of his youth.

Even as he was shuttling off to Cohasset as a kid, Burgess says, he wasn’t spending much time in white stretches of Boston. He would hang out with friends at the Corner Mall in Downtown Crossing but didn’t venture elsewhere downtown. And South Boston was not an option. “You were told as a kid, ‘You just don’t go there,’” he says. “‘You have enough trouble in life, don’t go find it.’”

The one night he does remember crossing into South Boston, to tow a car with his father, the pair were greeted with racist heckling. “We had to hurry up,” he says. “Get in and get out.”

Analyses of cell phone GPS data found that while there is little difference in the number of places people from white, Black, and Latino neighborhoods visit, there are big differences in where they go.Craig F. Walker/Globe Staff

That history, Burgess says, means he doesn’t know the streets of South Boston and other white neighborhoods with booming real estate markets as well as he might.

“I always ask my friends, ‘Why is it that Black brokers are not selling in the Seaport like they sell in Roxbury, Mattapan, Dorchester?’ And it’s really — I think we’re just not familiar with the intricacies of the neighborhoods,” he says. “Can you learn it? Yes. Can you go there, could you sell there? Yes. But it doesn’t feel as natural.”

The city has shifted, of course, since Burgess was a child. As an adult, he has ridden his bike through South Boston on occasion. He sees more people of color in parks and restaurants in whiter parts of town. And last year he affiliated with Compass, a high-end realty firm, in the hope of breaking into more lucrative markets.

So far, though, he’s still operating mainly in Black Boston. The city has opened up, but it has a long way to go.

How long?

Sampson and several co-authors developed a measure they call the “segregated mobility index” that assesses how evenly residents of a given city visit neighborhoods with different racial compositions — adjusted for the demographics of the city.

Boston landed in the 46th percentile, meaning that about half of America’s largest cities are more segregated in their movements and half are less segregated. That “belies a certain kind of reputation,” Sampson says, of a city hopelessly divided along color lines.

Indeed, Boston scored better on this measure than a number of cities that are widely considered more tolerant and cosmopolitan, like New York, Los Angeles, and Miami.

But that’s the glass-half-full view. The glass-half-empty view is that a city in the middle of the American distribution is still a highly segregated city.

“I wouldn’t say . . . [Boston is] doing well,” says Sampson. “All I’m saying is, it’s even worse in half the other cities.”

And it appears that our movements only grew more segregated with the pandemic.

A recent paper by researchers at New York University shows that after COVID restrictions went into effect last year, residents of the country’s 25 largest cities had less interaction with people of different racial and economic backgrounds.

And even when the tightest restrictions were lifted later in the year, people didn’t return to their pre-pandemic travel patterns — suggesting we may have reached a “new equilibrium” of enhanced segregation.

Mobility and murder

Everyone misses out when they travel only in familiar circles.

But the heaviest burden of our segregated movements falls on lower-income people of color.

For one recently published paper, Sampson and co-authors Brian Levy and Nolan Phillips built two measures of neighborhood health — one they dubbed “residential neighborhood disadvantage” and the other “triple neighborhood disadvantage.”

Residential neighborhood disadvantage is a static measure that uses traditional yardsticks like poverty rate, unemployment rate, and the share of households headed by a single parent to demonstrate something about the state of a neighborhood.

Triple neighborhood disadvantage is more dynamic. It considers not just the state of a given neighborhood but also that of the neighborhoods its residents visit and the neighborhoods that send visitors their way.

Residents of a triply disadvantaged neighborhood, then, aren’t just surrounded by poverty in their immediate environs. They’re also traveling to poor neighborhoods regularly and receiving visitors from similarly situated places.

In city after city, the data shows, there is a broad swath of neighborhoods that look highly disadvantaged by traditional measures and an often smaller group that stand out on the triple neighborhood disadvantage scale. These are the especially disadvantaged places — cut off from much of the wealth, wonder, and opportunity of better-off neighborhoods.

Here in Boston, there are three patches: One starts in Codman Square, near Burgess Realty, and stretches west along Talbot and Woodrow avenues toward Franklin Park. Another is in the Bowdoin-Geneva section of Dorchester. The third extends from Franklin Park north through Grove Hall and beyond.

It was on the edge of that Grove Hall-area cluster that Warren Daniel Hairston was found shot to death, at age 21, on a frigid day in January 2007.

“My Danny,” as his mother Ruth Rollins still calls him, loved to draw. Had a dry sense of humor.

And he spent his life shuttling among some of the region’s poorest, most racially isolated places.

He lived in Brockton and Mattapan and maintained close ties to his mother’s old stomping grounds in Dorchester and Roxbury.

Some of his best friends, Rollins says, were in the Grove Hall area. And he found plenty of trouble there before he met his end.

Would his life have been longer if it had stretched beyond the region’s poorest neighborhoods? It’s impossible to say, of course.

All the same, some of Sampson’s most alarming research shows that our segregated mobility patterns are strongly correlated with elevated murder rates.

Here in Boston, according to data compiled for Ideas, nearly half of the neighborhoods that scored worst on the triple neighborhood disadvantage measure had at least one homicide in a roughly two-year stretch spanning most of 2019 and 2020, compared with one-third of those that did poorly on the traditional residential neighborhood disadvantage measure. And there were similar findings in the other 36 large American cities the researchers studied.

Preliminary research by Sampson and his colleagues indicates that triple neighborhood disadvantage is tied to the spread of COVID as well.

That suggests it’s not just poverty that explains violence and disease transmission. It’s tight connections between some of the most impoverished neighborhoods — and the isolation of those neighborhoods from the city beyond them.

The findings resonate with Rollins, who has built a life as an anti-violence activist since her son’s death.

These days, she helps women with sons and brothers on both sides of street violence through the We Are Better Together, Warren Daniel Hairston Project.

She says much of the work of curbing violence — and healing from it — can and must be done in the most seriously affected neighborhoods.

But she has seen the value in getting out, even for a few days.

She recently hosted her fourth annual retreat at Rolling Ridge Retreat and Conference Center, situated on a 38-acre property of hills, trails, and open space on Lake Cochichewick in Andover. And the place has a certain magic, she says: “There’s something about bringing those women outside the city. When they’re surrounded by water and grass and canoeing — it’s so healing.”

Rollins says she wishes she owned a permanent space out in the country. Somewhere she could take these women on a regular basis.

Somewhere she could take young men like her late son.

She got a glimpse of what an escape could mean for Danny just before he died, when she brought him on a cruise.

He chatted with the kids on the islands they visited. Posed for a formal portrait at the Captain’s Ball. And talked with his mother about the hard things — her history of substance abuse and what he’d been up to on the street.

Rollins says he returned home pledging to look for work and turn his life around. But he was killed before he could try.

His mother used the picture from the Captain’s Ball for the likeness on his headstone.

‘Is the grass real?’

Not every journey outside the neighborhood is rejuvenating.

For one study, researchers at Ohio State University gave GPS-enabled smartphones to 506 Black adolescents in Columbus and sent them short surveys several times a day asking if they felt safe.

The research, presented at an American Sociological Association meeting but not yet published, shows Black boys often felt unsafe in whiter areas, likely because they expected “increased scrutiny, surveillance, and even direct targeting.”

Ohio State sociologist Christopher Browning says still-developing technologies, like sweat patches that measure cortisol levels in real time, may allow researchers to develop even finer-grained measures of the stress Black young people feel moving around the city.

But what we know already, he says, is enough to raise questions about the downsides of exposure to whiter areas. “Are there health implications to these exposures?” he asks. “Are [young people] experiencing greater levels of physiological stress? Is this exacerbating a sense of alienation?”

At least some of the poor outcomes typically attributed to young people’s experiences in their own neighborhoods, Browning says, may be rooted in their experiences in better-off places.

Still, he says, that’s no argument for Black kids to stay away from predominantly white neighborhoods. It’s an argument for making those neighborhoods — and their marquee institutions — more welcoming.

Here in Boston, a number of the city’s leading institutions have taken steps in recent years to broaden their appeal — gearing more events and exhibits toward people of color.

And there has also been a movement in Black and brown Boston to claim space in parts of the city that have long felt off limits.

A few years ago, Amplify Latinx, a group that aims to build Latino political and economic clout, held its launch event at the Edward M. Kennedy Institute for the United States Senate in a conscious effort to say that Latinos, too, should walk the halls of power.

This summer, a group called Boston While Black hosted a “Family Reunion” event at The Lawn on D in South Boston.

And last month, long-time community activist Thaddeus Miles staged a “Black Joy” gathering in the Seaport.

Performer Dzidzor Azaglo (left) and Nieisha Deed were moved to dance at Black Joy Day 2021 on Sept. 9.Pat Greenhouse/Globe Staff

There were live performances behind the Institute of Contemporary Art. A Black-owned fitness studio offered an exercise class. And festival-goers kayaked on Fort Point Channel — many of them for the first time.

“We’re not in enough spaces,” says Miles. “We’re all focused on Roxbury, Mattapan, Dorchester, when this city is much bigger than that.”

Black people need to get out to unfamiliar neighborhoods, he says, and carve out places “for us to be authentically who we are, to drop some of those masks.”

It’s all part of what Imari Paris Jeffries, executive director of King Boston, which is building a memorial to Martin Luther King Jr. and Coretta Scott King on Boston Common, calls a quest for “spatial justice.”

But one-off events, however powerful, can only go so far.

And a school in the heart of one of Boston’s triple disadvantage hotspots is aiming for something more sustained.

Codman Academy Charter Public School is the brainchild of long-time educator and activist Meg Campbell.

As a lecturer at Harvard’s Graduate School of Education in the early 1990s, she helped develop a new model of schooling known as expeditionary learning.

One of the core tenets was getting kids out of the classroom on a regular basis for immersive, real-world problem-solving.

Schools soon opened in New York City; Portland, Maine; and Dubuque, Iowa. And in 2000, Campbell proposed one on the grounds of Codman Square Health Center.

A year later, it was up and running.

Today, Codman Academy is best known for its symbiotic relationship with the health center. Part of the school is still housed there. The students do internships on site, and about a quarter of them are patients.

But the school reaches out of the neighborhood, too. Not for field trips, school leaders like to say, but for fieldwork.

The K-12 school has especially deep partnerships with the Huntington theater company and Harvard Medical School; the students work with these institutions — often at these institutions — on a weekly basis.

On a recent Friday morning, a group of 15 sophomores — all dressed in Codman Academy T-shirts and sweatshirts — showed up for class at a Huntington-operated space in the South End. Scuffed floors, a peeling tin roof, and a piano in the back.

They stretched: “Pop your booty back,” said Regine Vital, The Huntington’s manager of curriculum and instruction. They did vocal exercises: “Toy boat, toy boat, toy boat.” And they sorted through monologues from the plays of August Wilson.

They’ll each perform one in December. And their teacher told them to pick a speech they could identify with.

Kimberly Mejia, 15, considered one by Black Mary from “Gem of the Ocean” and another by Eli, from the same play. The description of Eli’s character said something about wrestling with life and death, and her own brother had died of heart disease when she was younger.

“I can relate,” she said.

Across town, a group of Codman Academy seniors showed up in purple scrubs for the MEDscience program at Harvard Medical School.

A high-tech dummy lay on a hospital bed, its chest rising and falling and its vitals showing distress.

Codman Academy students Isabel McDowall (left) and Abinorah Lauzama work to diagnose a dummy patient during Harvard Medical School’s MEDScience program on Oct. 1.Erin Clark/Globe Staff

Julie Joyal, the executive director of MEDscience, gave voice to the patient, using a microphone tucked behind mirrored glass. “I’m having a really hard time breathing,” she said, between coughs.

The kids knew what to do. Ask the dummy about her family history. About any medications she was taking. About the run she was taking when the breathing trouble started. Narrow it down.

When the patient had an acute breathing problem, and her voice rose, and the beeping of the machines seemed more intense, the students took action — administering asthma medication that saved her life.

There would be more trips to the Harvard Medical School campus in the weeks to come. But this was the first. And there was still something foreign about the whole experience. After seeing the sprawling quad amid the tall marble buildings, one of the students asked, “Is the grass real?”

Another, Nefertitti Myers, said that when they had been walking to the campus that day, people “were just staring at us. It felt uncomfortable.” But the students had been out in the city enough, through Codman Academy, to push beyond that discomfort. To feel they had a right to the space.

“It’s more like, ‘I know what I’m doing here, so mind your business,’” said Myers, with a chuckle.

And the experience of crossing that line into a new place, seeing it all, working on that dummy patient — it felt energizing.

Too much time in your own neighborhood and similar neighborhoods “makes you feel like that’s all you’re ever going to see, that’s all you’re ever going to be,” said student Dahnier Hall-Rodrigues. “When you step out of that Dorchester area — now you’re in different areas like Harvard — it makes you feel like you can step out of that box.”

David Scharfenberg can be reached at david.scharfenberg@globe.com. Follow him @dscharfGlobe.