The Lincoln Institute of Land Policy has released a policy focus report, Inclusionary Housing: Creating and Maintaining Equitable Communities. The Executive Summary opens,

After decades of disinvestment, American cities are rebounding, but new development is often driving housing costs higher and displacing lower-income residents. For cities struggling to maintain economic integration, inclusionary housing is one of the most promising strategies available to ensure that the benefits of development are shared widely. More than 500 communities have developed inclusionary housing policies, which require developers of new market-rate real estate to provide affordable units as well. Economically diverse communities not only benefit low-income households; they enhance the lives of neighbors in market-rate housing as well. To realize the full benefit of this approach, however, policies must be designed with care. (3)

The report uses the term inclusionary zoning to refer to

a range of local policies that tap the economic gains from rising real estate values to create affordable housing—tying the creation of homes for low- or moderate-income households to the construction of market-rate residential or commercial development. In its simplest form, an inclusionary housing program might require developers to sell or rent 10 to 30 percent of new residential units to lower-income residents. Inclusionary housing policies are sometimes referred to as “inclusionary zoning” because this type of requirement might be implemented through an area’s zoning code; however, many programs impose similar requirements outside the zoning code. (7)

The report notes that

Policy makers are understandably concerned that affordable housing requirements will stand in the way of development. But a review of the literature on the economics of inclusionary housing suggests that well-designed programs can generate significant affordable housing resources without overburdening developers or landowners or negatively impacting the pace of development. (4)

The report is obviously addressing two of the most important issues facing us today — the housing affordability challenge that many households face as well as the increasing stratification of communities by income and wealth.

There is a lot of value in the survey of the academic literature on inclusionary housing policies that is provided by this report. At the same time, there is some fuzzy thinking in it too. For instance, the report states that, “As the basic notion of supply and demand suggests, the addition of new units in a given market will inevitably put some downward pressure on the cost of existing units. But the larger effect tends to be upward pressure on housing costs because new homes are primarily built for higher-income residents.” (12)

This analysis ignores the well-accepted concept of filtering in urban economics. Filtering describes the process by which occupants of housing units go from higher-income to lower-income as the unit ages, becomes outdated and is subject to wear and tear. If higher-income households move to the newest housing, then other another household, typically of lower-income, can move into the vacant unit. If the number of households remains constant, then housing prices should decrease as housing development increases.

Because the real world does not look like an economic model, many people think that new housing causes increased housing prices. But the cause of the increased housing prices is often the same thing that is causing new housing construction:  increased demand.

Take NYC for instance. In recent years, it issues permits for 10,000-20,000 or so new units of housing a year, but its population has grown by about 60,000 people a year. Combine this with the fact that new housing construction is both a sign and result of gentrification in a particular neighborhood, it is no wonder people think that housing construction pushes prices higher. While this is an understandable line of thought for the man or woman in the street, it is less so for the Lincoln Institute.

My bottom line: this is worth a read, but read with care.