To understand how rising rents punish families of modest means, look no further than the queen-size bed that Jessica Jones and her three children share in her mother’s living room, where each night brings a squirming, turning tussle for space in a house with no privacy. Ms. Jones and her daughter Katelen, 14, anchor the sides like human bed rails, with two younger girls tucked in between. Joy is a 4-year-old featherweight, but Destaney, at 6, kicks so much that Ms. Jones binds her in a mermaid blanket. The day’s tensions lie beside them, and midnight sneezes are shared events. After two years of doubling up, Ms. Jones longs for a place of her own. But even though she works full time for the state government, a modest apartment would consume more than half of her income, a burden most landlords find disqualifying and one she could not sustain. With $41,000 a year in earnings and child support, she is, by government definition, not poor — just homeless. “My anxiety is through the roof,” she said. “I feel almost hopeless.” Unaffordable rents are changing low-income life, blighting the prospects of not only the poor but also growing shares of the lower middle class after decades in which rent increases have outpaced income growth. Nearly two-thirds of households in the bottom 20 percent of incomes face “severe cost burdens,” meaning they pay more than half of their income for rent and utilities, according to the Harvard Joint Center for Housing Studies. Among working-class renters — the 20 percent of people in the next level up the income scale — the share with severe burdens has nearly tripled in two decades to 17 percent. For both groups, the proportion with severe cost burdens has reached record highs. “More people, higher up the ladder, are facing impossible trade-offs,” said Whitney Airgood-Obrycki, a researcher at the Harvard Center. The federal government deems shelter affordable if it takes 30 percent or less of household income, a goal that only about half of the nation’s 44 million renter households meet. In consuming half or more of a family’s income, severe rent burdens steal from essential needs like food and medicine. They destroy the ability to save. They force frequent, destabilizing moves, unsettling parents at work and children in school. They flood fragile households with stress. “Housing insecurity ripples through every domain of family life,” said Stefanie DeLuca, a sociologist at Johns Hopkins University. “It’s this constant mental and emotional tax.” The growing burdens coincide with the declining reach of federal housing aid. Since 2004, the number of households served by the main programs for the poorest renters — public housing, Section 8 and Housing Choice Vouchers — has fallen by 6 percent, the Harvard analysis found, while the number eligible has soared. Ms. Jones, who moved in with her mother after her landlord did not renew the lease on a subsidized apartment, said the displacement had wreaked family havoc. Her mother complains that rambunctious children fill the house with noise. Katelen’s moods darkened and her grades dived. Sleepless and anxious, Ms. Jones took a medical leave, then passed out and suffered a concussion. “I felt like I was going to die, I was so stressed out,” she said. Similar stories abound in Charleston, which illustrates the forces that have raised housing costs nationwide. The problem is not that poverty has grown but that prosperity has spread in unequal fashion, bidding up rents and leaving behind families of modest means as federal aid declined. Jacqueline Drayton, a longtime Verizon worker, skipped meals to rent a suburban house that exhausted more than 60 percent of her income, then got laid off. Latoyia Cruz-Rivas thought she could handle an apartment that consumed more than half her income as a school bus driver. After an eviction proved her wrong, she lived in her car with her son and their dog. As the Joneses’ crisis stretches into its third year, Katelen’s singing has become a source of daily conflict. As a performer at church and an arts charter school, she considers singing her greatest joy, but her grandmother calls it noise. As doors slam and tempers flare, the housing crisis spills into the driveway, where her big voice fills a parked car and she forgets how long her family has waited for shelter it can afford. “I feel so stuck,” she said. “But singing helps me feel free.” People who spend half their income for shelter have no room for error. A few canceled work shifts or an unexpected car repair can leave them short. That poses special peril in South Carolina, where landlords can evict any tenant who pays even a single month’s rent more than five days late. Ms. Cruz-Rivas discovered the risk. A school bus driver from Greensboro, N.C., Ms. Cruz-Rivas, 42, moved to Charleston during the coronavirus pandemic, drawn by significantly higher wages and a desire to distance her teenage sons, Jevon and Amon, from troublemaking friends. She did not realize that rents were higher, too. With utilities, her apartment took more than half of her income, but, she said, “I figured, ‘I’ll make it work.’” For a while she did, if barely. But her hours shrank as more drivers returned to work after the pandemic, and Jevon’s job at Pizza Hut did not fill the gap. Federal pandemic aid staved off one eviction threat. Then came the kind of cascading misfortune that can put tenants on the street. Her sons totaled her car. The state suspended her commercial driver’s license. In the weeks it took to reinstate it, she lacked an income, and her landlord moved to evict her. Amon moved in with his girlfriend. A school social worker who serves homeless families, Sonya Jones, arranged motel stays and a donated car. When the motel money ran out, Ms. Cruz-Rivas and Jevon began living in the car with their dog, Koffi. Ms. Cruz-Rivas, who takes pride in her lack of self-pity, faced the ordeal with odd cheerfulness. “There’s people in worse situations than us,” she said. They slept in a parking lot and used the restroom at the all-night convenience store where Jevon found a job. Having survived childhood sexual abuse, she added, “I can train my mind to accept anything.” Reclining in the car one night this fall, Ms. Cruz-Rivas scrolled through social media while Jevon watched football on his phone with Koffi at his feet. “We just lay back and chill,” Ms. Cruz-Rivas said. “We talk, laugh, joke,” Jevon said. Their matching tattoos read “family first.” It would have made a homey scene if home wasn’t an old Toyota. Ms. Cruz-Rivas switched jobs to a limousine service, where her clientele of businesswomen and bachelorettes had no idea their upbeat driver slept in her car. An eviction record makes Ms. Cruz-Rivas a pariah in the rental market, but Jevon, now 20, joined a waiting list for subsidized housing. After months of homelessness, he landed an apartment where they can sleep without hitting the steering wheel. Thirty miles from the parking lot where Ms. Cruz-Rivas slept, Jacqueline Drayton has a four-bedroom house in suburban Summerville, where traffic stops for geese crossings and residents car-pool in golf carts. But she grapples with the same affordability crisis. With shelter costs consuming most of her income, Ms. Drayton, the former Verizon worker, said the burden depresses everything from her food budget to her psychological health. “It’s nerve-racking,” she said. “Sometimes I don’t know if I’m going to make it.” The shortage of affordable housing may seem perennial, but the problem has changed. In 1960, shelter took 28 percent of the average renter’s income (though some was so bad it lacked indoor plumbing). Now it takes 41 percent of income — and for poor renters, 75 percent. Ms. Drayton’s father, James Earl Drayton, was one of nine firefighters honored as heroes after their deaths in a 2007 fire. But she notes that he gave his life for a city with little housing she can afford. Concerned about violence, Ms. Drayton left the city eight years ago when she was married and two incomes covered suburban rent. Divorce changed the math. With earnings of about $42,000 and little child support, she moved with four children to a house that consumed roughly two-thirds of her income. Suddenly everything revolved around rent. She skipped meals to pay it. She used tax refunds to pay it in advance. She felt anxious before she paid the rent and depleted afterward. Her post-divorce depression deepened. “Rent definitely took over everything,” she…