America is known as the land of opportunity. But new research suggests that the American Dream is much harder to reach for some kids and that wide differences exist even for those who grow up in neighborhoods mere miles apart.

Researchers from Harvard University, Brown University and the U.S. Census Bureau this month launched the Opportunity Atlas, an interactive map of various outcomes — from income levels to rates of incarceration and teen pregnancy — and the characteristics of children's early lives. The research, based on tax and census data, looks at people born between 1978 and 1983 — now 34 to 40 years old — and maps their chances of upward mobility by the neighborhoods of their youth.

The researchers said the latest research doesn't attempt to say why differences occur. But they found those differences can be stark depending on where children grow up, as well as their race.

"The fact that neighborhoods matter means that either you can change where kids grow up, or perhaps, more importantly, you can change places," said one of the lead researchers, Harvard economics professor Nathaniel Hendren. "What we can say is that there are places that are producing lower incomes for children who are growing up there, and that should motivate us to think about how we can improve those places."

The researchers say that although the project is still in its early stages, they hope it will increase understanding of the impact of past policies and help target new ones. For example, the Chicago Housing Authority experimented in the 1990s with moving some voucher holders into neighborhoods with lower poverty rates. The researchers credit that change of environment for kids' higher earnings later in life compared with those whose families didn't make a similar move.

The research effort, known as Opportunity Insights, has its critics. In a March talk at Princeton University, University of Chicago economics professor James Heckman questioned the reliability of the data and argued for additional measures of mobility. He also said he thinks the research puts too much emphasis on neighborhoods and he worries people will see racial causes for disparities where other factors may be to blame.

"I'm not denying racial bias. I'm sure there's lots and lots of racial bias," Heckman said. "But I do worry, especially in the current environment, where's there's so much tension, so much feeling, so strong, that somehow we're going to rush to judgment on something that's fundamentally important for understanding public policy."

Rahim Kurwa, an assistant professor in the department of criminology, law and justice at the University of Illinois at Chicago , said the research was valuable but that it was important for conversations to get past "good and bad" neighborhoods and develop better strategies to bring success across the board.

"When we say that a neighborhood has failed its children, we're not talking about the neighborhood itself. The underlying actors there are the political and the social institutions themselves," Kurwa said. "And it's empowering to be able to say that: A neighborhood is not a concrete thing and we can change policies."

In consultation with Hendren's team and other academic experts, the Tribune identified several takeaways that explore what happened to Chicago-area kids of a generation ago and what that could mean for children in the area today. Visit the interactive mapping tool at www.opportunityatlas.org.

Takeaway 1 White kids more likely to reach top income level One measure of class mobility is rising from childhood poverty to become a top earner as an adult. In the blue and green tracts on these maps, children from poor families who grew up there had better chances of earning an income in the top 20 percent nationally. The red and orange areas show tracts where fewer such children achieved that feat. White children in Cook County rose out of poverty to become high earners more often than their black peers. On average, 1 in 5 white children from low-income families grew up to have a household income in the top 20 percent nationwide for all races, according to the data. Only 2.8 percent of black children and 8.2 percent of Hispanic children from a similar financial background experienced that kind of upward mobility. Neighborhoods where children had good chances to far out-earn their parents as adults existed throughout the area, the research found. For example, 10 percent of low-income black children from a tract in West Ridge on the Far North Side reached the top 20 percent of incomes nationally, a good outcome for that subgroup. (Twenty-eight percent of low-income white children from that tract achieved the same feat.) But stark racial differences remained even when comparing the best neighborhoods for black mobility — those where poor kids were most likely to reach that top income tier — with the worst neighborhoods for white mobility. Black people who grew up poor in the top 1 percent of tracts for mobility earned about $30,000 as adults on average, which is less than the $32,000 for whites born to poor families living in the worst 5 percent of tracts, according to tax records from 2014 and 2015 cited in the research. Looking at adult income more broadly, white children in Cook County also grew up to make more money on average than black children, even when comparing kids whose parents were of the same financial means. White children from high-income families made about $62,000 on average as adults, whereas their black peers made an average of $32,000. In middle-income households, it was $51,000 for white children vs. $27,000 for black children; for low-income children, $43,000 vs. $21,000. "Clearly, the biggest correlation there is related to race, and there are gonna be a lot of other factors that are similarly related to that," said Geoff Smith, who heads the Institute for Housing Studies at DePaul University. "That's why Chicago in a lot of ways is 'easy' to understand. The pattern is really built into the geography of race in the city." The researchers' findings regarding racial differences in mobility have received the most attention, leading Heckman to caution against using just one definition of upward mobility or assume that racism is at the heart of these differences. "It's not just the income of the parent," he said in an interview. "It has to do with a whole range of social and economic conditions including parenting, mother's education, single-parent home." Damon Jones, a professor at the University of Chicago Harris School of Public Policy, also cautioned that the income rankings for parents and their children may not be immediately comparable. "What does it mean to be at the 25th percentile in the 1990s vs. in the 25th percentile now? They may not mean the same thing," he said. "Another piece, even harder to measure, is wealth."" Explore the maps Mobility map for black kids Mobility map for white kids Adult income for black kids Adult income for white kids

Takeaway 2 In parts of Chicago, poverty is persistent This map shows how common it is for children who grew up in persistently poor areas to earn little money as adults. In the marked census tracts, the average household income was low in 1990 and remained low in more recent years. Most of those tracts are red, indicating a low average income for the adults who grew up there, even though many moved away. To UIC researcher Matt Wilson, the data reflect a sad reality: deeply entrenched poverty in certain parts of the city. Mapping the data shows many neighborhoods where families had little money decades ago and produced kids who make little money as adults. And even though many of the kids have moved away, these neighborhoods continue to house families that make little money. Wilson said these areas illustrate the long-lasting, generation-to-generation nature of poverty. "What's discouraging is that, if you grew up in these neighborhoods, we know what your life trajectory was. But we still know in 2016, a lot of these issues are still the same," said Wilson, a senior research specialist at UIC's Great Cities Institute. For example, one census tract in Englewood, just west of where the Dan Ryan Expressway splits from the Chicago Skyway, had one of the nation's lowest median household incomes in 1990 — roughly around the time the kids being studied were in elementary or middle school. By the time kids from low-income families in this tract grew up, many had moved away but typically still earned far less than other kids who grew up in low-income homes across the country. As adults, they had an average annual household income of about $18,000, according to the 2014 and 2015 tax records. In that tract the median household income recorded in census records from around the same time was close to that number, about $15,000 a year. Explore the maps Pockets of entrenched poverty An Englewood example

Takeaway 3 No boost for poor kids from gentrifying Lincoln Park area A significant number of kids from low-income families still lived in this section of Lincoln Park in the 1980s. Despite the gentrification in the area, the orange color of this tract shows their income as adults remained low. Most of them moved out of the neighborhood. Lincoln Park became one of the city's first models of gentrification, largely pushing out low-income residents from east to west. By the 1980s, the data suggest, one pocket of western Lincoln Park still housed a significant number of kids from low-income families, but most of those children had left by adulthood. By the latest census measure, this section — known as Sheffield Neighbors — has become among the wealthiest in the country, with a median household income of $110,000 for adults. The low-income kids who grew up there years ago, however, now live in households making only about a quarter of that, roughly $27,000 a year. That didn't even keep pace with those from low-income families nationally. DePaul geography professor Winifred Curran said that while it matters where kids grow up, the geographic coordinates aren't the most significant factor. In a gentrifying area, for example, the low-income families who used to live there largely got pushed into lower-income areas afterward. "People who grew up in this neighborhood, even though it ends up becoming a wealthy neighborhood, aren't themselves becoming wealthy," she said. Hendren said it's too soon to say whether gentrification had a negative effect on the upward mobility of kids from low-income families, although the question is ripe for research. DePaul's Smith agreed, adding that policymakers need to think of what happens to low-income families who could be forced out. "If you're gonna invest in those neighborhoods, there has to be some consideration of housing stability for lower- to moderate-income folks." Smith said. "Either create affordable options in places of opportunity or preserve them in areas you're trying to invest or improve." Explore the maps A Lincoln Park example

Takeaway 4 Some Chicagoans stay very close to home The widespread blue areas on the first map show that it was quite common for kids from the Chicago area to live as adults in the same region. People were less likely to live in the exact tract where they grew up, the second map shows, but that happened quite frequently on the Southwest Side. Most people who were raised in Cook County three decades ago still live as adults somewhere in what the researchers call the Chicago "commuting zone" — which includes the collar counties plus Grundy and Kendall counties — though usually not in the census tract where they grew up. About 1 in 5 adults still lived in the same tracts they knew as kids, while 76 percent were somewhere in the commuting zone. Many true homebodies can be found on the Southwest Side. About a third of people who grew up in a broad area including Bridgeport, Armour Square, Little Village, McKinley Park and Back of the Yards lived in the same census tract where they grew up — tracts often just a few miles wide. Rates tended to be much lower east of the Dan Ryan; for example, only 7 percent of children from one tract in the Douglas neighborhood stayed there. In Cook County, Hispanic children were the most likely to still live in the Chicago commuting zone as adults, at 84 percent. For black children, the figure was 73 percent. The least likely to stay in the area were American Indians, at 67 percent. Explore the maps Staying in the area Staying in same tract A contrasting tract

Takeaway 5 Race, income and the chances of imprisonment In an area of Chicago where incarceration rates tend to be high for people born into low-income families, a tract just north of Douglas Park stands out for a lower rate. According to the data, incarceration rates in Cook County were highest for black men, regardless of financial background. Nearly 1 in 10 black men in Cook County were incarcerated at the time of the 2010 census, while less than 1 percent of white men were incarcerated. (Very few women of any race surveyed were incarcerated countywide.) Differences in parental income may contribute to this discrepancy. Boys from low-income families of all races were more likely to be imprisoned than other groups: 5.9 percent of such kids were incarcerated during the 2010 census, compared with 2.6 percent of boys from middle-income families and 1.1 percent of boys from high-income families. But black boys born to well-off families were still more likely to be incarcerated than white boys born to low-income families in Cook County, 4.4 percent to 1.8 percent. Generally, low-income stretches of the city had higher incarceration rates. But children in those neighborhoods were not uniformly prone to be behind bars as adults. Fifteen percent of low-income kids who grew up in a six-by-eight-block tract that encompasses Douglas Park were incarcerated later on. In a neighboring tract north of Roosevelt, the figure was less than 1 percent of low-income kids. Incarceration rates have been a major focus of studies on mobility, but there's debate about their importance. Heckman sees incarceration as a far-reaching factor that could help explain the gap in income gains for children across multiple generations, much more than where people grew up. The Opportunity Insights researchers argue that incarceration plays less of a role because, they say, pronounced racial differences in earnings exist even when comparing kids from high-income families who have lower incarceration rates as adults. Jones of U. of C. said being able to map out the imprisonment rates by census tract was valuable in itself. "You can't overstate the fact of how much data you have at your hand if you just want a snapshot," he said. "To be able to do that for all census tracts in the country, that's pretty impressive." Explore the maps Black male incarceration rates White male incarceration rates A surprising tract