LOS ANGELES - It’s a common sight in Los Angeles. Thousands of people living in tents on sidewalks, sometimes with trash piled outside their makeshift shelters, conditions that breed typhus and other diseases.

Analysts say the problem is complex, has been decades in the making and that a response requires coordination at many levels of government. President Donald Trump and his White House Council of Economic Advisers have recently weighed in, and Trump, on a flight to California for political fundraisers on Tuesday, said California's largest cities are destroying themselves through an inadequate response to the problem. On Monday, California Governor Gavin Newsom and local officials asked Trump for help in providing emergency rent vouchers.

Homelessness has risen 12% in Los Angeles since 2018, despite a healthy economy that some critics say has left too many behind. Nearly 60,000 people were living without shelter in the most recent count of the country’s homeless residents in January.

“What’s unusual now is that you had a massive surge of jobs and wealth back into the cities after this long trend of suburbanization,” said Kevin Klowden, executive director of the Milken Institute’s Center for Regional Economics and California Center. He says sprawling commuter cities like Los Angeles and San Francisco viewed their downtown regions as business hubs, not residential ones. That pushed housing prices up and drove workers ever further from their jobs, while cities failed to create incentives for building new housing.

The result in Los Angeles, Klowden says, are emergent shantytowns in the form of tent cities.

For many residents, sudden unemployment or major health problems, sometimes compounded by drug and alcohol addiction, can leave people with few options.

“As soon as something catastrophic happens, then they're liable to be pushed over the edge," said John Maceri, CEO of The People Concern, a nonprofit social service agency.

That happened to Robert Venegas, 58, who fell on hard times after the death of his wife and spent two years on the streets.

“I was living in a tent, wherever I could lay my head,” he recalled.

He is now staying in a 45-bed shelter called El Puente, one of a series of shelters being established throughout the city. This one near L.A.’s historic center overlooks a busy freeway that carries commuters to and from the suburbs.

Last year, Los Angeles moved more than 21,000 people from the streets and into permanent housing financed by two measures approved by city and county voters.

“The fact that they can put their head down at night and be able to sleep and feel that they’re safe and secure where they are, versus having to be up all night worrying about whether they’re going to be attacked on the streets,” that makes a big difference, said Daniel Xavier, who manages the El Puente housing facility where Venegas was staying.

Housing backlog

Many homeless people like Venegas are awaiting permanent housing.

The Los Angeles Homeless Services Authority, a public agency set up by the city and county, is tasked with tackling the problem. The organization has a backlog of tens of thousands of people “ready to be housed,” lacking only housing units, said executive director Peter Lynn.

Lynn said Los Angeles is not the most expensive city in the United States, but it has the biggest gap between incomes and cost of living, and is “the least affordable housing market in the United States.” The root cause? “We have under built housing for decades,” said Lynn.

One reason is the aversion of Californians to high-density housing. But most agree that such attitudes will have to change, since there is limited space for sprawling, single-level homes close to the city center.

New York, a city of high-rise apartments, has done better with its homeless than Los Angeles or San Francisco, said Klowden, who noted that a harsher winter climate is part of the reason.

“When you know that people are going to die on the streets because they’re going to freeze, you’re incentivized to act,” he said. In Los Angeles, “people have been able to push the problem down the road for a long time.”

Homelessness in Los Angeles is reaching crisis proportions, however, and “we need to really look at all the tools in the toolbox and find ways to streamline housing production,” Maceri said.

Experts agree that getting people off the streets requires changes in policy at every level of government, and creative thinking.

The Trump administration is weighing in. The White House Council of Economic Advisers has prepared a report that blames the housing crisis in California — where nearly half of the nation’s unsheltered homeless live — on overregulation of the housing market, including zoning regulations, rent controls, historical preservation or environmental mandates.

In a Sept. 10 letter to Trump, Los Angeles Mayor Eric Garcetti cited other causes of homelessness: “An ever-higher cost of living, a national economy that has hollowed out our middle-class and federal government cuts to vital housing funds and social services.”

“We hope,” Garcetti added, “the federal government can be part of the solution.”