For years, Joan Burke has had to battle the fact that homelessness, for most Americans, is an invisible scourge. Recently, however, invisibility hasn't exactly been the problem.

Ten minutes' walk from where she works, at the homelessness charity Loaves and Fishes, in Sacramento, California, lies an all-too-visible "tent city" - a shanty town, built on wasteground beside railway tracks, that has become one of the most prominent symbols of the recession.

Tent cities reminiscent of the "Hoovervilles" of the Great Depression have been springing up in cities across the United States - from Reno in Nevada to Tampa in Florida - as foreclosures and redundancies force middle-class families from their homes.

"Where the tent city is now is literally a toxic waste dump, it's unsafe, but these people are very resourceful," Burke said. "Some people are living in squalor, with just a tarp tied to a chainlink fence. But then you'll see someone with several tents: The tent they live in, plus some outbuilding tents. And they couldn't be more neat and more tidy. They're working hard to create a sense of home."

Many of the 200 residents of Sacramento's Tent City, as with those around the country, are not recent victims of the downturn: They are the chronically homeless, some of them mentally ill. But the encampment seized national attention after Oprah Winfrey featured it on her daytime television show, part of a series of reports she has been running on the "new faces" of homelessness.

Embarrassed by an influx of television crews, Arnold Schwarzenegger this week announced plans to house the tent-dwellers in a nearby convention centre until a $1m (£690,000) plan for more permanent shelter can be implemented.

The California governor told reporters he had "personally delivered a letter to President Barack Obama last week, to request that economic stimulus funds for the homeless be fast-tracked".

Obama grappled with the phenomenon on Tuesday, when a reporter at his primetime news conference asked him about the "tent cities sprouting up across the country". The president said he was "heartbroken that any child in America is homeless", adding: "The most important thing I can do on their behalf is to make sure their parents have a job."

In both the number and types of inhabitants, the new tent cities do not equate to the homelessness of the 1930s. But the symbolism is powerful, and may have significant political consequences. It was not all that far from Sacramento, or from Fresno - home to another Californian tent city - that the celebrated Depression-era photographer Dorothea Lange took her haunting photos of families living in makeshift camps, forced west by the collapsed economy and the Dust Bowl further east.

"We all take care of each other," Michelle Holbrook, a 34-year-old resident of the Sacramento camp who lost her job as a carer, told the San Jose Mercury News. "I've become the camp mother: I do most of the cooking, and make hot water for coffee." A resident of Reno's tent city, Tammy, said: "We eat things that other people throw out, or whatever ... It's really embarrassing to say, but that's the way it sometimes is out here." Another Reno tent-dweller, Jim, told one of Oprah's reporters it was "like learning how to live all over again".

Obama's stimulus package includes $1.5bn for emergency shelters, and, if passed, his budget should significantly expand funding for affordable housing. Philip Mangano, director of the US Interagency Council on Homelessness, has called the stimulus funds "manna from heaven", saying they would boost his two-pronged strategy of preventing homelessness while rapidly re-housing those who fall victim to it. Last year, the US government reported that homelessness in America had declined by 30% between 2005 and 2007.

Burke, whose organisation provides food and shower facilities for Sacramento's Tent City residents, has mixed feelings about the national media exposure. It may help build support for addressing the problem, she said, but also threatens to reinforce a distinction between the "deserving" victims of the recession and those who have been homeless for longer, and for other reasons.

"It's an oddity of human nature that we are more about people who have suffered for a short time, rather than people who have suffered for a long time," she said. "When we can identify with somebody's situation, obviously, our empathy is engaged quickly: You can look at someone and say, 'You know, goodness, they owned their own home, they look like I do.' But if someone's been homeless for a while, they no longer look like we think we look. If you're living in a tent, it doesn't take long before you're somewhat unkempt and dirty, because you're living in the dirt."

The changing economy has, accordingly, thrown very different kinds of people into close quarters with one another. In Fresno, freelance electricians and truck drivers, employed until months ago, rub shoulders with crack addicts and those with serious psychological problems. There have been reports of violence in one part of Fresno's encampment, known as New Jack City, but Burke said what really impressed her in Sacramento was the degree of cooperation.

"There is a sort of very pure democracy and self-governance at play. People are making up the rules of their cluster of tents, deciding what's permitted, just as in any sort of community," she said. "You don't want to romanticise this - it isn't camping - but there is a community, and there is a sense of helping others. We've had a series of storms here recently, and if there's somebody new who doesn't have a tent, people will take them in. It's that understanding that, you know, there's somebody worse off than I am."