Allison Gibbons has lived a lifetime of problems.
A difficult childhood in a broken home. An eating disorder, drug abuse, depression, alcohol - "obviously I was self-medicating," she says.
The Kansas City, Missouri, woman is the mother of a young son whose father is in jail.
Today she works for a better life, with dreams of becoming a nurse.
"I know it's going to be a struggle," she says.
It's a strain Mary Jo Vernon understands.
Thirty years ago she was a single mother with three small children and three jobs, hoping others in the grocery store didn't notice her food stamps.
"I was trying to keep my nostrils above the waterline," Vernon recalls.
Education, hard work and public support marked the road back. Today, Vernon earns a six-figure salary as the health director of Platte County, Missouri- a married, doting grandmother with grown, thriving children.
Mary Jo Vernon embodies the American dream, the deeply held belief that anyone who works hard and follows the rules can succeed.
Yet studies show that dream has been fading for decades.
Now experts believe meaningful mobility may be dangerously close to disappearing entirely. A wealth gap and stagnant growth have made success increasingly an accident of birth - more like feudal Europe than can-do America.
Social scientists are scrambling to learn why. And they're advancing theories: financially divided cities, missing fathers, crumbling social institutions, broken politics. Those long-standing problems now take on a heightened urgency.
It's clear the old questions and answers have failed, at least in part. Even Vernon's success shows how far apart the rungs on America's ladder to success are spaced.
"It feels some days like the American dream is slipping away," she said.
REAL INCOME STAGNANT
Economists, politicians and academics have spent years examining the growing wealth gap among the rich, the middle class and the poor in America. They found that real income for all but the highest earners has barely grown for three generations.
Less noticed is the ongoing slump in social mobility, the ability to transcend one's circumstances and achieve greater success.
Americans see rags-to-riches opportunity as their birthright.
"Upward mobility from the bottom is the crux of the American promise," former Indiana Governor Mitch Daniels, a Republican, said just a few years ago.
Yet studies repeatedly suggest Americans face steeper odds of escaping poverty than their counterparts in other modern economies. Some studies show children in France, Japan and even Pakistan stand a better chance than US children to rise above their parents.
"There are an awful lot of people who are struggling, who will never get out of poverty," says Stephanie Kelton, an economist at the University of Missouri-Kansas City.
"It's roughly three times harder to get from the bottom into the middle, or from the middle into the top, in the US as it is in a place like Japan or some of the Nordic countries."
Americans, President Barack Obama said last December, think "their kids won't be better off than they were. ... This is the defining challenge of our time."
He and others have offered some responses: a higher minimum wage, more job training and education, a broader social safety net.
Experts worry that such efforts stumble because policymakers rely on outdated assumptions and ineffective repairs.
What if stable, two-parent families and financially integrated neighbourhoods are more important for mobility than nutrition programs or job training? How might communities of faith and fellowship bind neighbourhoods closer together?
Fully answering those questions will prove enormously difficult, researchers caution.
"It will be 10 years or more before we have anything close to a consensus" on reasons and remedies for social immobility, said Lane Kenworthy, a sociology and political science professor at the University of Arizona.
Yet finding the answers is critical.
"Americans can tolerate a lot of inequality compared with people of other nations," write researchers Anthony Carnevale and Jeff Strohl, "but only if everyone has a chance at upward mobility."
Patrick Sharkey, a sociology professor at New York University, agrees: "This realisation that the United States ... is unique in how low its level of mobility is, that's kind of eye-opening to a lot of people."
'BITTER AND ANGRY'
Mary Jo Vernon's journey from poverty to success began early. She grew up in a home built by her father, helping to care for a sister with Down syndrome.
"My goals were pretty small," she recalls.
Her challenges grew dramatically as an adult when her marriage fell apart.
"Just trying to keep the lights on and water running and the groceries coming in was all I could do," she said.
Vernon and her children might have fallen into a poverty trap too deep to escape. It's a desperation all too familiar to Bianca Hunter, a single mother raised in a single-parent home.
"It's almost impossible. It really is," she said. "That's why people are so bitter and angry and why kids don't get the attention from their parents that they need."
A Kansas City area child has just a 7 percent chance of moving from the bottom fifth of earners to the top fifth, according to a landmark 2013 study by the Harvard University Equality of Opportunity Project.
The national average - 8 per cent - is less than half that of Denmark.
A child born in the bottom fifth of incomes in Memphis has just a 2.8 per cent chance of reaching the top fifth, the worst urban performance in the nation. By contrast, a similar child in San Jose, California, has a 12.9 per cent chance of achieving the top rank of earners.
"The US is better described as a collection of societies, some of which are 'lands of opportunity' with high rates of mobility across generations," the Harvard researchers write, "and others in which few children escape poverty."
One explanation for that pattern is a history of racial segregation. Places with mobility problems often have a history of dividing the races.
Researchers increasingly believe economic segregation - the tendency of wealthy people to live with others equally wealthy, or for the poor to live with other poor - better explains why social mobility stalls.
A 2013 study by the Pew Charitable Trusts concluded that "the most economically segregated US metro areas - those where the very rich and the very poor live far from each other - are also the least economically mobile, and vice versa."
A wider range of incomes within a closely knit neighbourhood, some researchers believe, builds the aspirations among the poorer children. At the same time, it helps convince higher earners to offer neighbours a hand up with better schools, health care and other services.
Vernon thinks her diverse neighbourhood played a role in her own escape.
"Exposure to range of incomes and wealth gives children a broad perspective on life," she says.
Mary Jo Vernon's recovery began when she returned to school - while raising three children.
"They couldn't have Nikes," she says. "They couldn't have Jordache."
But the quartet would often study together in the evenings, giving the young students an early lesson in focus and discipline, key skills learned in the home and at school.
Kansas City's struggles with providing K-12 public education are well-known. Decades of underperforming public schools provide at least a partial explanation for lower social and economic mobility in the community.
"One thing we know matters is schools," said Kenworthy, the social scientist. Good schools "do help equalize opportunity."
In 2012, the 34-nation Organization for Economic Co-operation and Development found that the U.S. was one of just three member countries spending less on disadvantaged students, on average, than wealthier students.
In 2012, according to data compiled by Kids Count, 35 percent of children nationwide lived in households like the one Mary Jo Vernon headed - just one parent.
Researchers increasingly believe stable, two-parent families are critical for social mobility.
"Having just one parent makes it harder," says Kenworthy.
The Harvard research team is blunt. "The strongest predictors of upward mobility are measures of family structure, such as the fraction of single parents in the area," it writes.
Most often, those single-parent families are run by a woman.
Conservatives say the breakdown of the traditional family explains much of the poverty trap, providing a rationale for making it harder to divorce and easier to deny benefits to single parents.
Republican Kansas Governor Sam Brownback has organised seminars on the topic and urged policies and legislation promoting two-parent families. Conservatives have suggested caps on benefits for single mothers or grants for low-income families with two parents.
Others say single-parent homes compare poorly because a second income is missing.
"You cannot do well in school if you're hungry," says Alice Lieberman, a researcher and professor at the University of Kansas. "You cannot work and function adequately if you're hungry."
Some researchers say the number of adults in a home matters less than stability and positive role models. Children with bickering parents, for example, may be more harmful to mobility than conflict-free single-parent households.
Shauna Love of Kansas City, 29, grew up in a home without a father. She now raises two children without a spouse.
"You definitely need two parents to raise a child," she says. "It is so much harder by yourself."
RELIGION CAN HELP
Asked to explain her triumph over poverty, Mary Jo Vernon mentions education and work.
Then: "My faith. My groundedness in a power greater than myself."
Social mobility researchers aren't completely sure why, but there is evidence that moving up the economic ladder comes easier in communities organised around faith - churches, synagogues, other gathering places for worship.
Salt Lake City, a community largely organised around the Mormon religion, is highly mobile.
Yet the influence of a church on social mobility is complicated.
Churches remain important institutions in many poor neighbourhoods, for example. Yet mobility is a problem because of other factors - education, family structure and the like.
Some communities considered more secular are still socially mobile. Boston and San Francisco are in the top 10 of socially mobile cities, Harvard says, but a Gallup poll puts both near the bottom of the list of the nation's most religious cities.
That suggests the influence of a church may be part of a broader picture, experts say. The goal is a strong community. Active engagement in civic life, strong social structures in neighbourhoods, an ethic of shared sacrifice and ambition all contribute to socially mobile populations.
Mary Jo Vernon had a strong faith, help from sympathetic friends and neighbours, a strong work ethic and a little luck.
She also had help from the community and government.
"I applied for food stamps, Aid to Families with Dependent Children, I got rental assistance," she said. "Medicaid. I got a Pell grant to go to school."
While social scientists agree on what helps mobility - economically integrated neighbourhoods, stable families, good schools - they say fully fixing the problem will require a broader approach than tackling any one concern.
Indeed, those studying social mobility - and those fighting to improve it - worry the emphasis on family, neighbourhoods and community may mean less support for other traditional tools: nutrition programs, for example, or rigorous job training and job creation.
"There are three reliable ways to help or 'lift' the bottom," writes economist Jared Bernstein. "Subsidies that increase the poor's economic security today, investment in their future productivity and targeted job opportunities at decent wages."
It involves more than just cash benefits. Recipients, some believe, must be convinced government programs can help.
"I felt like more than dirt," Vernon recalled. "But you know what? When people use it for what it's designed for, it's a very good tool."
At the same time, government aid can be a trap - a snare acknowledged by some who get benefits today.
Bianca Hunter is studying to be a radiologist. To pursue her education - and feed her son - Hunter relies partly on government assistance, just as her mother did.
Generational dependence on government aid is a common feature of uniformly poor neighbourhoods, researchers say, because information on available support programs travels quickly from parent to child and from neighbour to neighbour. Eventually it becomes a multigenerational habit.
"You have people who settle," says Hunter. "I don't want to settle. I don't want to depend on the government."
NO 'POLITICAL WILL'
All of this leaves policymakers in a tough spot.
What works in one city might not work in another.
Addressing any one shortfall might not change the others.
Liberals and conservatives increasingly say social mobility should top the country's to-do list.
Yet researchers deeply doubt the political class has the patience or imagination to carry out better ideas.
"All of the areas that you talk about that might predict mobility - neighbourhoods, schools, health care, infrastructure - we could shore some of those things up," KU's Lieberman says.
"But we do not have the political will, and wealthy people do not have the desire."
Still, people who have battled the poverty trap - Shauna Love, Mary Jo Vernon, Allison Gibbons, Bianca Hunter - show that while the American dream may be in trouble, American dreamers remain.
"It takes a village to raise a child," Love said. "But remember: It's your village. You're controlling the village.
"You can do anything you set your mind to."
-Kansas City Star