LESS THAN 2 percent of Montgomery County’s land is zoned for apartments, and an average single-family home there, in Maryland’s most populous locality, sells for $700,000 — out of reach for most below the upper middle class. With home prices soaring and little new inventory being built, it’s no wonder that Montgomery officials are desperate to expand affordable housing options.

The Montgomery County Council recently did so unanimously, loosening previously draconian restrictions on building and renting out basement and garage apartments on single-family lots. As a modest measure to chip away at a system of exclusionary zoning and land-use rules, the vote should not have been controversial. It was, owing mainly to inflamed opposition from a relative handful of residents and the characteristic obstructionism of Marc Elrich, the county executive who has made a career of courting NIMBY groups by resisting sensible ideas.

The move may result in no more than a few hundred additional units of housing added annually, a drop in the bucket for a jurisdiction of more than 1 million people.

Some of the apartment dwellers will be older children moving back in with their parents, or grandparents who want to be close to their adult children. Relatively few are likely to have children going to the county’s overcrowded public schools, a stated objection raised by some who railed against the new rule. (Other opponents attacked it along thinly veiled racist and classist lines, including the Republican political consultant who told The Post that Montgomery “could end of up like Prince George’s,” the neighboring county that is predominantly African American and middle- class, or the writer of a letter to the editor in The Post, who said Montgomery was at risk of becoming “a slum.”)

No doubt, many opponents were anxious that their stable and settled neighborhoods would become less so. Still, current housing trends — specifically, the shortage of affordable housing — are raising alarm bells nationally.

In December, Minneapolis ended single-family-only zoning, meaning apartments and multiple dwellings can now be built on any available plot. In the D.C. region, the Metropolitan Washington Council of Governments last year warned that projected job growth is outstripping forecast housing supply at such a rate that, by 2045, localities will need to add 100,000 homes to those already anticipated to sustain economic growth.

Mr. Elrich contends that the new rules will do nothing for low-income renters, who will be unable to afford the new units. That’s probably true; it also misses the point.

In Montgomery, as in other places — San Francisco is a cautionary tale — middle-income residents, not just the poor, are being squeezed out by soaring prices. The county already spends tens of millions of dollars annually to preserve low-income housing and subsidize low-income renters; the cost of doing so is exorbitant: more than $100,000 per unit, by some estimates.

By contrast, the council’s move to ease rules on building so-called accessory apartments costs taxpayers almost nothing and promotes affordable options for middle-income renters. In the face of a severe affordable-housing crunch, that’s a smart and timely move.

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