State officials in California, alarmed at the growing number of homeless encampments popping up in cities across the state, will ask voters for permission to spend at least $1 billion of their money for new facilities to treat mental illness and addiction among the residents of those encampments.

In an announcement Sunday, Governor Newsom said he wants to “modernize how California treats mental illness, substance use disorder and homelessness” by asking voters in 2024 to sign off on the issuance of new bonds to pay for facilities across the state to treat as many as 10,000 homeless people.

The ballot measure would reform the state’s Mental Health Health Services Act, which levies a one percent tax on earnings over $1 million on residents of the state, to allow use of the money to treat drug addicts in addition to those with mental health issues. The tax generates $3.8 billion in annual revenue for the state.

“This is the next step in our transformation of how California addresses mental illness, substance use disorder, and homelessness — creating thousands of new beds, building more housing, expanding services, and more,” Mr. Newsom said in a statement. “People who are struggling with these issues, especially those who are on the streets or in other vulnerable conditions, will have more resources to get the help they need.”

Earlier in the week, Mr. Newsom — under fire from civic and business leaders who say the encampments are making life increasingly dangerous and untenable in many cities — announced that he would use the state’s National Guard to assist in the delivery of some 1,200 so-called “tiny homes” in Los Angeles, San Diego, San Jose, and Sacramento. Mr. Newsom said he was setting aside an additional $1 billion for that initiative.

California is often described as the epicenter of American homelessness, accounting for as much as a third of the nation’s unhoused population. A recent survey by the Department of Housing and Urban development said as many as 171,000 of the country’s nearly 600,000 homeless are scattered around the Golden State.

Many of those homeless have overrun its largest cities, taking shelter in makeshift tent cities that line busy highways and city streets, sleeping openly in central business districts, threatening local residents, and using public transport as toilets or so-called “shooting galleries” for drug use.

An annual survey by the Public Policy Institute of California released last month found that an overwhelming number of California residents — 70 percent — said the number of homeless people in their communities has increased in the past year. About 20 percent said it was the single most salient issue facing the state at the moment.

California is not the only state struggling to cope with the proliferation of homeless encampments. Egged on by a Texas-based think tank, the Cicero Institute, started by a co-founder of Palantir, Joe Lonsdale, dozens of cities and states are looking at outlawing public camping altogether in order to force the homeless off the streets and into shelters.

Mr. Lonsdale started Palantir, a big data company, with billionaire political activist Peter Thiel, who has bankrolled several candidates affiliated with President Trump, including Senator Vance of Ohio and Blake Masters in Arizona, who lost his Senate bid in 2022.

Texas led the charge to wipe out homeless encampments when in 2021 it passed a law modeled by the Cicero Institute that made public camping a Class C misdemeanor subject to a $500 fine and threatened to strip cities that ignore the law of state funding. Missouri passed a similar bill last year, and at least five other states — among them Oklahoma, Arizona, Georgia, Kansas and Wisconsin — are considering similar measures.

The Cicero Institute has been critical of efforts to reduce homelessness by building new housing for those currently camping on city streets — the so-called “Housing First” solution — saying such spending benefits politically connected housing developers while ignoring the root causes of the problem, drug addiction and mental illness.

“San Francisco built enough permanent housing to house every single chronically homeless individual in the city back in 2011,” an analyst with the institute, Judge Glock, wrote in 2022. “Yet instead of ‘ending homelessness,’ as then-Mayor Gavin Newsom had promised, homelessness increased substantially until the city became an international byword for the homelessness crisis.”

City leaders who stand to benefit from Mr. Newsom’s plans to build additional housing, however, remain undeterred. “All different types of housing — small homes, motels, hotels, and more — are needed to urgently confront this crisis,” said Los Angeles Mayor Karen Bass. “This housing will help us bring more people inside, which is what our city needs right now.”