This November, Bay Area voters will decide on an unprecedented $20 billion bond measure to help build or preserve potentially 90,000 affordable homes across the nine-county region.

On Wednesday, the Bay Area Housing Financing Authority board, a regional body made up of local elected officials, unanimously agreed to put the measure on the ballot.

“This is one of the most significant votes I’ve ever taken in my career, and that’s saying a lot,” said San Francisco Supervisor Hillary Ronen. “Housing should be a human right.”

Across the Bay Area, some 1.4 million residents — 23% of all local renters — spend more than half their income on rent, classifying them as “severely rent-burdened,” according to regional officials. Meanwhile, an estimated 37,000 people in the region are homeless on any given night — more than the entire population of Menlo Park.

Ahead of Wednesday’s vote, housing advocates and nonprofit developers urged board members to send the bond measure to voters. They said a massive new investment in affordable housing is needed to balance the region’s staggering inequality and help move its most vulnerable residents off the street.

But opponents at the public meeting in San Francisco argued the bonds would be paid for by a painful tax increase, which would inevitably lead to wasteful public spending without genuine accountability. Some also raised concerns about what the region’s continued push to build more affordable housing could mean for public services, congestion and homeowners’ property values.

“I’m mad as hell, and I’m not going to take this anymore!” said longtime San Mateo County resident Tom Weismiller, quoting fictional news anchorman Howard Beale from the 1976 film Network.

The bonds would be repaid by a new property tax on homes and businesses. The financing authority estimates the average annual tax would be $19 per $100,000 of assessed property value, or about $190 a year for a home valued at $1 million. The tax is expected to last through 2078.

The total cost of the bonds with interest is estimated at around $48 billion.

As it stands now, the bond measure would need a two-thirds majority of all Bay Area voters to pass. However, if voters approve a separate measure on the same November ballot to make it easier to pass certain tax increases, officials said the bond measure would need only 55% approval.

Still, despite widespread agreement that the Bay Area needs to build more affordable housing, the bond measure’s passage is far from guaranteed, as voters continue to feel the sting of inflation and grow more skeptical that public officials can solve the region’s most pressing challenges.

According to a recent poll commissioned by the finance authority, 54% of voters would support the bond measure, below the threshold needed to pass. At the same time, 68% said local taxes are already high enough and would vote against any tax increase, though pollsters explained some of those voters also expressed support for the bond measure.

“Voters right now are very pessimistic,” said Ruth Bernstein, chief executive of EMC research.

But a recent string of successful city and county affordable housing ballot measures won voter support after officials and advocates campaigned for them.

San Francisco alone has approved four bond measures since 2015, totaling $1.47 billion. Voters in Oakland, Berkeley, Alameda County and Santa Clara County have together authorized billions of dollars for affordable housing in recent years. Those measures required a two-thirds majority to pass.

The decision to send the bond measure before voters comes as the state is pushing Bay Area cities and counties to approve more than 441,000 new homes by 2031, a roughly 15% increase in the region’s total housing stock. More than half the homes must be affordable to low- and middle-income residents.

If approved, the $20 billion bond measure would allocate $4 billion to creating a regional fund to finance affordable projects. The rest would be split among the Bay Area’s nine counties and five of its largest cities to determine how to boost affordable housing. An oversight committee would be created to track the spending.

This is a chart showing the amount Bay Area counties and cities would receive from a proposed $20 billion regional housing bond. San Francisco and Santa Clara County would receive $2.4 billion at the high end, and at the low end Napa County would receive $118 billion.Santa Clara County would receive $2.4 billion, San Mateo County $2.1 billion, Alameda County $2 billion and Contra Costa County $1.9 billion. San Francisco would see $2.4 billion, San Jose $2.1 billion and Oakland $765 million.

Affordable housing is reserved for those earning less than a specified amount, generally a percentage of an area’s median income. That can be as much as 120% of the median income or as low as 15% or 30%. In Santa Clara County, 30% of the median income is $38,750 for a single person, according to the state housing department. Residents typically spend about 30% of their income on housing costs, though the amount can vary.

The finance authority estimates that 45% of new units created by the bond would be for residents earning less than half the median income.

In addition to housing, local officials could use the bond money to help build homeless shelters, including tiny homes, motel conversions, group shelters and managed-encampment sites.

Earlier this year, San Jose, which under Mayor Matt Mahan has made building new shelters the centerpiece of its homelessness response, agreed to spend about 28% of its potential bond money on shelter options. Mahan, a voting member of the finance authority board, has argued affordable housing is too expensive and takes too long to build to be the main strategy to fight homelessness.

“It’s not either/or — it’s both,” Mahan said in a statement. “As we increase shelter capacity, we will require people to come indoors and end the era of encampments.”

Staff writer Kate Talerico contributed to this report.