As wealth disparities in the United States have reached Dickensian proportions, housing disparities have followed. Condo developers are creating increasingly lavish apartments for the super-rich, while those with modest budgets find themselves priced out of city centers.

That’s an issue not only for housing advocates, who lament the human toll of housing stratification, but also for mayors who believe their cities’ futures depend on attracting “young creatives.” One solution is to encourage the building of micro-units, apartments of about 300 square feet or less.

Developers see a profitable niche in these tiny units, which can command higher prices per square foot than conventional studio apartments, especially if they come with amenities aimed at tech-savvy 20-somethings (a group that seems willing to trade bedwidth for bandwidth). But to permit such units, cities have to ease minimum square footage requirements, well-intentioned vestiges of an era when eliminating tenement conditions was important.

In San Francisco, supervisor Scott Wiener has introduced a proposal that would reduce the city’s minimum apartment size from 290 to 220 square feet. The change, expected to come to a vote in late September, would pertain only to new construction, so landlords don’t chop up existing rentals.

But even 220 square feet may not be the limit. Patrick Kennedy of Berkeley developer Panoramic Interests has created a 160-square-foot prototype apartment in a Berkeley warehouse. In San Francisco’s SoMa (South of Market Street) neighborhood, Panoramic is creating twenty-three 300-square-foot units, prefabricated in a factory in Sacramento. (The building is expected to be complete in time for the Greenbuild convention in San Francisco in November.) Panoramic has been looking at several other markets—including Washington, D.C., Chicago, Santa Monica, California, and Portland, Oregon, Kennedy said.

In Boston, Mayor Thomas Menino has been promoting the Seaport Square neighborhood as an “innovation district”; small apartments, he has said, are “a crucial part of the equation.” With his support, Portland-based developer Gerding Edlen is turning a former warehouse building at 63 Melcher Street into 27 small (if not micro) apartments, each 400 to 500 square feet, that the company is marketing as “innovation units.” Principal Matt Edlen says the building will have meeting and office facilities meant to help its residents build new businesses.

New York has gone even farther by setting aside a publicly owned lot in the Kips Bay neighborhood for some 80 micro-units. Developer-led teams had until September 14 to respond to the city’s request for proposals. But detailed renderings on the city’s website suggest it had already decided what the building should look like. That’s one reason several architects interviewed said that, while initially interested in the project, called adAPT NYC, they chose not to participate. And there were others. “New York City designers relish the opportunity to re-think anything, especially housing,” says Henry Smith-Miller, of Smith-Miller and Hawkinson Architects. “So we wanted to enter the competition. But we approached a number of residential developers, who all decided to pass, saying the project was too small, meaning not very profitable.”

Celia Imrey, principal of Manhattan-based Imrey Studio, gave a different reason for sitting this one out: She believes small units should be integrated into buildings that contain a variety of unit types. “The micro-unit is a great idea, but not as a building typology,” she says. (And there’s no sign the city would consider anything as radical as designer Aaron Cheng’s plan for micro-units that fold up into parking spaces when the owners aren’t home, a project he submitted for the James Dyson Award.)

Not everyone is on the micro-bandwagon. Sara Shortt, executive director of the Housing Rights Committee of San Francisco, worries that allowing tiny units could start cities down a “slippery slope” of undoing zoning regulations that protect the public. But that seems unlikely—even the smallest micro-units are bigger than dorm rooms, and safety requirements aren’t being relaxed. In New York, for example, a developer who proposes sleeping lofts above kitchenettes will have to ensure that both the upper and lower “levels” are within the reach of sprinklers.

A more legitimate concern is that the current crop of micro-units aren’t exactly affordable housing, just, in Shortt’s view, another way for the creative class to enjoy city centers. Traditionally, young innovators have moved to urban edges, where they have helped depressed neighborhoods rise. By creating micro-units in places like New York’s Kips Bay and San Francisco’s SoMa, the cities may be doing nothing more than increasing the concentration of the privileged in already-desirable enclaves—not the most enlightened urban planning goal.