Many experts say homelessness is not an intractable problem.
A national focus on housing veterans and people who have long been homeless has made a difference, for example. But methods to end it or significantly reduce the problem come with financial and political hurdles. A look at some of the key strategies and their challenges:
FEDERALLY FUNDED SUBSIDIZED HOUSING
A shortage of housing that's affordable to very low-income people, especially in high-rent areas, is a key reason for homelessness. Providing more affordable housing can sometimes prevent it.
"We don't need a multi-billion dollar homeless system," said Paul Boden, a longtime advocate for the homeless who runs the San Francisco-based Western Regional Advocacy Project. "We need to reinvigorate our housing systems."
But nationally, that's not the way things are headed.
For the last 40 years, there's been slow growth in the number of units in publicly subsidized housing, and President Donald Trump's budget proposal calls for reducing vouchers.
An analysis by the liberal-leaning Center on Budget and Policy Priorities found that 235,000 fewer families could have access to subsidized housing under his plan. The cuts would not be as deep under budget plans being considered in Congress.
The study's author, Douglas Rice, believes that perhaps 5 to 10 percent of families that lose vouchers would become homeless.
LOCALLY SUBSIDIZED AFFORDABLE HOUSING
Building more low-cost housing is at the center of efforts to stem homelessness in Los Angeles and other West Coast cities.
Since last year, voters in Los Angeles and Los Angeles County have approved bond issues totaling about $4.7 billion over 10 years to build more affordable housing, using tax increases to pay for the bonds. Voters in the counties that include Oakland and San Jose have approved similar measures.
Joe Colletti, CEO of the Hub for Urban Initiatives, which provides planning and other services in several California communities, said the approach is the right one. But it will take years to build homes.
He said voters might be disappointed when they still see people living on the streets in a decade: While adding 10,000 units of housing in Los Angeles can prevent homelessness for many, he said, it won't get everyone who is now homeless off the streets.
In many places, officials have added laws to combat panhandling, camping in public places and stepped up enforcement of those and other policies to keep homeless people away.
In August, Sacramento County officials approved spending $5 million to increase enforcement of an anti-camping law along the American River, which is lined with encampments.
That's discouraging for Bob Erlenbusch, executive director of the Sacramento Regional Coalition to End Homelessness. He says there aren't enough efforts to house the growing numbers of homeless people.
Some advocates compare stepped-up law enforcement to "whack-a-mole." People might be pushed out of one area. But if they don't have another place to go, they'll pop up elsewhere.
More than a decade ago, the federal strategy shifted from shelters and transitional housing toward providing permanent homes for people experiencing homelessness.
The rules and conditions make shelters unappealing for many people: Many have rules banning drugs and pets, and some would-be clients consider them unsafe or uncomfortable.
There tend to be more of them in places with more severe winters. And in New York City, Massachusetts and Washington, D.C. — all places with high per-capita homeless rates — there are policies requiring shelters be available to many people experiencing homelessness.
How to help or get help locally: Sonoma County Continuum of Care