For a complicated policy problem, the California housing crisis can be explained simply: People want to live in California, and Californians don’t want them to.

A powerhouse economy, along with a forgiving climate and other less tangible attractions, has sustained high demand for California housing across the decades. But the state’s residents and their elected representatives have collectively engineered an equally impressive suppression of the housing supply that, particularly in the Bay Area and coastal Southern California, has only deepened in recent years.

For every 1,000 residents California has gained since the 1970s, it has produced only 325 homes, a report by McKinsey & Co. noted, which is less than a third of New York’s pace and half of New Jersey’s. To match the number of homes available per person in those states, both of which have relatively limited housing supplies for their populations, California would need another 2 million. To match the national average, it would need 2.5 million.

The most widely felt consequence is that, as the state Legislature’s nonpartisan research arm put it, “Housing is more expensive in California than just about anywhere else”: The median home price of more than half a million dollars is twice the national average, and rents are at a similar premium. The state’s homeownership rate ranks last in the nation, and, when housing and other costs of living are considered, its poverty rate ranks first. Nearly half the country’s unsheltered homeless live here.

Having long ignored or enabled the forces that created the housing shortage, the Legislature will try to confront them when it reconvenes Monday. The most important and controversial legislation under consideration, Senate Bill 35, would require cities that haven’t met housing needs to expedite approval of multiunit residential developments that meet zoning and other conditions. Authored by state Sen. Scott Wiener, D-San Francisco, the bill aims to eliminate some of the myriad opportunities for the state’s cities and towns to prevent homes from being built. As such it would represent the Legislature’s first serious attempt to address the housing crisis where it lives.

Even when new housing doesn’t face the kind of fierce local opposition that greeted large-scale development proposals in Bay Area communities such as Brisbane and Los Gatos, residential construction proceeds haltingly in California, if it proceeds at all. While one survey found that the average U.S. building permit is issued in 4½ months, the Legislative Analyst’s Office reported the typical wait is seven months in the Bay Area and more than a year in San Francisco.

“Even within the group of highly regulated cities, the Bay Area stands out,” said UC Berkeley economist Enrico Moretti, who has studied and written extensively about housing supply restrictions.

Opposing development makes sense for incumbent homeowners, whose property grows more valuable as the shortage worsens. They have often been joined, in what Moretti called a “bizarre alliance,” by renters and activists who attribute rising rents in poorer neighborhoods to development — even though it’s the overall lack of new construction that drives gentrification. By excluding people from the Bay Area and other regions where jobs and income are plentiful, local restrictions lead to a loss of income on a statewide and national scale while shifting wealth from workers to landowners. “That’s why it makes sense for us as a state to step in,” Moretti said.

SB35 has come closer to doing so than a comparable proposal by Gov. Jerry Brown last year partly because legislative leaders and the governor are coupling it with bills enabling billions in government spending on affordable-housing programs, a more popular approach among the Legislature’s ruling Democrats. But as the Legislature’s own researchers have noted, “the scale of these programs — even if greatly increased — could not meet the magnitude of new housing required.” Based on past results, for example, a $3 billion bond measure under consideration wouldn’t produce enough homes to close a year’s worth of the continuing gap between the demand for and construction of new housing.

The bill has also won support through a number of concessions that make it more difficult to predict its impact. It could slow the projects it means to expedite, for instance, by requiring builders to pay union-set wages. And it leaves local governments with too many options for stalling the sort of developments it’s supposed to enable.

“It’s difficult to project which places this will be a useful tool and how easy it will be for cities to get in the way of it,” said Kristy Wang, community planning policy director for SPUR, a San Francisco urban planning think tank that supports the measure. “In some ways, it’s circumscribed so tightly that a lot of cities don’t have a lot to worry about.”

The bill’s reliance on existing local zoning and the state’s assessment of regional housing needs could also limit its ability to dramatically increase development, said Nicholas Marantz, an assistant professor of urban planning and public policy at UC Irvine. Still, Wang said, it could make a significant impact by giving more local officials a sort of excuse to approve housing under state duress.

It will probably take this reform and more to change a local political calculus that treats housing largely as a burden to be resisted. While it goes without saying elsewhere, much of California has to be convinced that, as Wang put it, “Housing is a good thing.”

This commentary is from The Chronicle’s editorial board. We invite you to express your views in a letter to the editor. Please submit your letter via our online form: SFChronicle.com/letters.

Legislature returns Monday — it’s time to act

Pass Senate Bill 35 to expedite approval of appropriate multifamily housing development, and rein in local government obstructionism. This is the most significant step lawmakers can take to accelerate housing construction.

Get rid of counterproductive provisions that drive up costs of new housing, such as union-pushed “prevailing wage” requirements. The housing shortage needs to be treated as a crisis that demands political courage.

Fund affordable housing to complement market-rate development, keeping in mind that easing private construction is the priority.

Consider further reforms that give local governments incentives to approve housing and reduce pointless barriers to building in developed areas.

Tell your legislators what you think: Find names and contact information for your state Senate and Assembly representatives at http://findyourrep.legislature.ca.gov.

Plans in the balance

California legislators have yet to take assertive action on the housing crisis. As the session nears a close, here’s what remains in the hopper:

Speed development: Senate Bill 35, by Scott Wiener, D-San Francisco, would expedite approval of urban, multiunit residential developments that conform to zoning, affordability and other standards in communities that aren’t meeting local housing needs.

Fund affordable housing: Senate Bill 2, by Toni Atkins, D-San Diego, would add fees of up to $225 per real-estate transaction to raise $250 million a year for affordable-housing programs. Senate Bill 3, by Jim Beall, D-San Jose, would ask voters to approve $3 billion in borrowing for those programs.

Dwelling on negatives

Californians’ myriad reasons for opposing new housing in their communities range from the familiar to the innovative.

Character study: “Proponents of the city’s small-town feel” have played a big role in stalling a Brisbane development, The Chronicle reported recently. “We would like to exist as we have existed in the character of our community,” said resident Clara Johnson.

This land is jobs land: In rejecting proposed teacher housing this month, San Jose officials argued that the land had to be reserved for commercial uses. “City officials said converting ‘jobs land’ to housing sets a dangerous precedent,” the Mercury News reported.

Shadow of a doubt: San Francisco officials required a redesign of a proposed South of Market apartment complex, The Chronicle noted in May, after neighbors and advocates complained that it would increase the amount of shadow cast on a nearby recreation center by one percentage point.

Creative differences: Oakland activists successfully demanded a $100,000 concession from a developer proposing to build an apartment tower on a downtown parking lot, the San Francisco Business Times reported last year, because it would obscure a mural.

With apologies to Potter Stewart: A Planning Commission member struggling to explain why a mixed-use development would not suit Los Gatos was quoted by the Silicon Valley Business Journal as saying, “I’d rather go to the Supreme Court definition of pornography: I don’t know what it is, but I know when I look at it. It (the proposed development) doesn’t look like anything I’ve seen in Los Gatos. ... I can’t connect the dots between the subjectivity and the data, but it doesn’t look like anything I’ve seen in town.”