Montgomery County, Md., which includes some of Washington, D.C.’s most affluent suburbs, has moved to allow more construction of basement and backyard apartments, sometimes known as in-law units or granny flats. Per the New York Times‘ Binyamin Appelbaum:

The [County] Council approved the new rules unanimously, making Montgomery County one of the largest jurisdictions to embrace what planners call “accessory dwelling units.” California passed a law in 2016 making it easier to add an apartment to a single-family home. In the following year, permits in Los Angeles jumped to nearly 2,000, from 90. Minneapolis, Seattle, neighboring Washington, D.C., and other cities also have rewritten their rules.

County leaders said they needed to provide more housing and a greater diversity of housing. Nationally, the share of households consisting of only one person has climbed to more than 25 percent in 2010, from less than 10 percent in 1950.

The changes apply only in three residential areas of the county, and overall seem fairly minor, to judge from Dan Schere’s piece at Bethesda Beat:

Detached ADUs must be limited to 10% of the lot area and no larger than 1200 square feet. Attached ADUs must be no larger than 1200 square feet; however, if the footprint of the principal structure is greater than 1200 square feet, an ADU may occupy the basement or cellar of that structure without a square footage limit.

ADU owners also must provide a parking space, except for structures within one mile of a Metro, MARC or future Purple Line light rail station.

County Planning Director Gwen Wright said in an interview that the ADU change could mean about 100 more units in the county.

That’s 100 more units in a county of an estimated 1.05 million population, set amid a metro area that continues to expand rapidly in employment and population.

Watching the controversy unfold in recent weeks, I’ve noticed that the proposals drew heated resistance from an interesting combination of opponents. Some were generally liberal residents up in arms over the prospect that newcomers might get to live in their sought-after neighborhoods at a lower cost of entry. Meanwhile, more politically conservative residents were up in arms because they don’t think the law should give private owners so much leeway to use their property as they see fit. Or have I gotten those rationales mixed up?

It happens, however, that the Washington, D.C. area is growing rapidly in population and there are few alternatives to permitting more density in one way or another. Writes a commenter on social media, “When we looked to buy a house in the DC area, we saw illegal basement apartments everywhere–MD, DC, NOVA. Densification comes, whether the government endorses it or not.”

If the county ever chose to get serious about accommodating more newcomers it would probably have to look at one of its more dubious land-use commitments, the 93,000-acre Agricultural Reserve. Since 1980 that greenbelt-like creation has caused development pressure to leapfrog up to the counties to the north, where much farmland is being converted to development as a result.

The Times piece quotes a retired lawyer who seems happy with the idea of continuing to steer newcomers further out toward greenfield housing developments with longer commutes rather than permit ADUs in her neighborhood. She

described living in the county as a privilege that people need to earn. “You work hard, and you get to go live in Montgomery County,” she said. “Does that mean it has to be the first place you live? No. You can drive a little further and work your way up to it.”

Or not, if property rights are allowed in this case to work more freely.