CHATTANOOGA >> At 7 in the morning, they are already lined up — poultry plant workers, housekeepers, discount store clerks — to ask for help paying their heating bills or feeding their families.

And once Metropolitan Ministries opens at 8 a.m., these workers fill the charity’s 40 chairs, with a bawling infant adding to the commotion. From pockets and handbags they pull out utility bills or rent statements and hand them over to caseworkers, who often write checks — $80, $110, $150 — to patch over gaps in meeting this month’s expenses or filling the gas tank to get to work.

Just off her 10 p.m. to 6 a.m. shift, Erika McCurdy needed help last month with her electricity and heating bill, which jumped to $280 in January from the usual $120 — a result of one of the coldest winters in memory. A nurse’s aide at an assisted living facility, McCurdy said there were many weeks when she couldn’t make ends meet raising her 19-year-old son and 7-year-old daughter.

"There’s just no way, making $9 an hour as a single parent with two children, that I can live without assistance," said McCurdy, 40, a strong-voiced, solidly built Chattanooga native.

She was so financially stretched, she said, that she and her daughter often sneaked into her son’s high school football games free during halftime because she couldn’t afford the $6 tickets. (She proudly noted that her son, Charles, had made the All State football team.) As for her daughter Jer’Maya, who mimics Beyonc?’s every move on her mother’s iPhone, McCurdy said, "She’d love to take ballet and piano lessons, but there’s no way I can afford that."

Having worked as a nurse’s aide for 15 years, McCurdy has been among the nearly 25 million workers in the United States who make less than $10.10 an hour — the amount to which President Barack Obama supports increasing the minimum wage. Of those workers, 3.5 million make the $7.25 federal minimum wage or less.

And like many of them, McCurdy hasn’t been able to rely on steady full-time hours — she has often been assigned just 20 hours a week. Even if she worked full time year-round, her $9 hourly wage would put her below the poverty threshold of $19,530 for a family of three.

Climbing above the poverty line has become more daunting in recent years, as the composition of the nation’s low-wage workforce has been transformed by the Great Recession, shifting demographics and other factors. More than half of those who make $9 or less an hour are 25 or older, while the proportion who are teenagers has declined to just 17 percent from 28 percent in 2000, after adjusting for inflation, according to Janelle Jones and John Schmitt of the Center for Economic Policy Research.

Today’s low-wage workers are also more educated, with 41 percent having at least some college, up from 29 percent in 2000. "Minimum-wage and low-wage workers are older and more educated than 10 or 20 years ago, yet they’re making wages below where they were 10 or 20 years ago after inflation," said Schmitt, senior economist at the research center. "If you look back several decades, workers near the minimum wage were more likely to be teenagers — that’s the stereotype people had. It’s definitely not accurate anymore."

In Chattanooga, the prevalence of low-wage jobs has contributed to the high poverty rate: 27 percent of the city’s residents live below the poverty line, compared with 15 percent nationwide. Women head about two-thirds of the city’s poor households, and 42 percent of the city’s children are poor, nearly double the rate statewide.

"The face of poverty in this community is women, especially women of color," said Valerie L. Radu, a professor of social work at the University of Tennessee, Chattanooga.

This city was not always a magnet for low-wage jobs. For much of the last century, the city, which hugs the Tennessee River, was a manufacturing hub with dozens of apparel factories, textile mills and metal foundries.

During the last quarter of the 20th century, almost all the factories and foundries were shuttered, and with them disappeared thousands of manufacturing jobs that had once lifted workers, even ones without high school degrees, into the middle class or to the cusp of it. In their place have come thousands of service-sector jobs: at the aquarium and Imax theater built to lure tourists and at hotels, nursing homes, big-box stores, brew pubs, fast-food restaurants, beauty salons and hospitals.

Discount stores dot the landscape, including a Family Dollar downtown near the upscale Bluewater Grille, reflecting how much U.S. cities have experienced a hollowing-out of the middle class.

"Chattanooga has a twofold problem: the low level of educational attainment and the traditional jobs that these people move into have largely disappeared," said Matthew N. Murray, an economist at the University of Tennessee. Just 23 percent of Tennessee adults have a bachelor’s degree.

JeraLee Kincaid, 23, is an $8.50-an-hour cashier who works at the checkout booth at a parking garage next to the Marriott Courtyard hotel downtown. A solid student in high school, Kincaid, who lives with her mother, planned to study computer programming in college, but instead her family decided that she needed to help pay the medical bills of a 5-year-old niece who has leukemia.

"She can’t eat, talk or walk by herself," said Kincaid. She says she feels stuck, but also grateful that her boss is trying to help find her a scholarship to attend college.

When Volkswagen opened a $1 billion assembly plant in 2011, 80,000 people applied for 2,000 jobs paying an average of $19.50 an hour. Many low-wage workers, like McCurdy — a high-school dropout who later obtained her GED — would have loved to work there, but they faced difficulty mastering the math tests given for jobs that involve advanced machinery.

"We understand that more individuals have to get some kind of higher education degree or certificate to have a chance in this world," said Chattanooga’s mayor, Andy Berke. "We don’t want the South to be a place where businesses go to find low-wage, low-education jobs. That’s a long-term problem that midsized cities in the South face."

Here as well as elsewhere, a college degree cannot guarantee a good job.

Landon Howard graduated from the University of Tennessee campus here four years ago with a bachelor’s degree in social work, but has been unable to find a job in that field. Instead he is a prep cook at the trendy Tupelo Honey Cafe. Often scheduled for just 15 to 20 hours a week at $9.50 an hour, he usually takes home less than $200 a week.

"I’ve had to move back in with my parents," Howard said. His most urgent concern is his lack of dental insurance. "One of my teeth is cracked," he said. "There’s a big gaping hole. I don’t know if I’m going to lose it."

McCurdy, as a parent in a modest income bracket, would not usually be eligible for the state’s Medicaid program, although her children would, but she was accepted because of a heart condition requiring costly medications.

Her family has had to make many sacrifices since she was laid off in 2012 from her job as a full-time nurse’s assistant in the emergency room of Memorial Hospital.

Her fall to $9 an hour at the assisted living facility from $13.75 at the hospital forced her to give up a 2,000-square-foot home in Harrison, a local suburb, "which is beautiful, and you have better schools," she said.

"It was a good life," she added. "You didn’t have to worry about violence or anyone breaking in."

After being laid off, "I realized I couldn’t afford to stay in a house where the rent was $625 a month," she said. So she found a $400-a-month, 1,100-square foot house in Brainerd, known for its gangs and violence. "I stay in at night," she said. "I put bars on the windows."

The new house has two modest bedrooms, a largely unfurnished living room, a bathroom and a small, shotgun kitchen "where I got to move the table when my son gets up from dinner," she said. "Imagine being in a two-bedroom place with a 6-2, 280-pound boy and a little girl. Me and my little girl share a room."

They also share a bed, but Jer’Maya keeps her dolls, books and clothes in Charles’ room, among his footballs and athletic gear. McCurdy receives $400 a month in food stamps. Without it, she said, "we wouldn’t be eating."

Still, McCurdy worries about her children’s future.

"I have a son that’s graduating in May," she said. "He’s looking at college. My heart is pounding 99 miles per hour. If he goes on full scholarship, I’ll still need to support him — how to pay his cellphone bill, how to pay for transportation and food during vacations."

Her February utility bill just arrived and it stunned her: $320. She may again turn to Metropolitan Ministries for help, although she says she hopes the $3,000 or so she expects to receive from the earned-income tax credit will help her pay that bill — and also buy a new living room couch.

Rebecca Whelchel says she has seen big changes in the clientele since she became the executive director of Metropolitan Ministries eight years ago.

"It used to be that folks came in with a single issue — it was like, ‘I have to buy a new tire because my tire blew out,’ or, ‘I’m short on my electrical bill,’" Whelchel said. "Now they come in with a rubber band around a bunch of bills and problems. Everything is wrong. Everything is tangled with everything else."

At age 34, Nick Mason earns $9 an hour as an assistant manager for a Domino’s, overseeing a crew of six. "I don’t think $9 is fair — I’ve been working in the pizza business for 19 years, since I was 15," he said.

He attended the University of Tennessee, Chattanooga, studying to become a registered nurse, but he dropped out as a sophomore when his marriage fell apart. He returned to work full time, and he and his children moved in with his parents in the suburb of Hixson.

"I just wish we could have our home, but I can’t afford to," said Mason, father of 7-year-old Halle and 5-year-old Eli. "That’s what the kids keep asking for."

"We’ve had to sacrifice a lot of things," he continued. "I’d love nothing more than to give them what they deserve. As a single father, it’s impossible. I put my kids in karate about a year ago. They loved it, but I got to the point where it was a choice between paying for a cellphone or karate, and as a manager, I need a cellphone for people to keep in touch with me."

Mason has heard the criticisms: Stop complaining about your pay; just go back to school and that way you’ll find a better-paying job.

"I would love to go back to school," he said. "It’s easy for people to say that because they haven’t been in my shoes. I’m already busy every minute of the day. I already don’t get to see my kids enough. I doubt I’ll be able to afford school, and I don’t know where I would find the time."

His big hope is to be promoted to run a Domino’s, which might mean earning $15 an hour.

McCurdy, who applied for two dozen jobs this winter, delivered good news with a big smile. She was offered a job as a full-time nurse’s aide on the transition medical floor at Erlanger Health System, a hospital.

"They’re paying me $10.64," she said, an improvement over the $9 an hour she had been earning. "That gives me a little room to breathe."

© 2014 The New York Times Company