- Public transportation and jobs in the Washington, D.C. region are highly centralized. New housing is not.
- Denser communities are attracting more housing growth
- Housing growth in the urban core means more apartments
- Shifting trends in housing growth are a mixed bag, environmentally speaking
- Data and methodology notes
The latest U.N. climate change report pulls no punches: Human activities are contributing to climate change “at a rate that is unprecedented in at least the last 2000 years.” And two of the largest components of household carbon footprints are transportation and household energy use, both of which are correlated with where people live.
More specifically, suburban households have larger carbon footprints than their urban counterparts, because they are more dependent on solo driving for commuting and non-work trips, travel longer distances, and live in larger homes, which require more energy to heat and cool. Low-density neighborhoods also require more—and more expensive—infrastructure to provide basic services such as water, sewer, and roads.
For the U.S., reducing harmful greenhouse gas (GHG) emissions will require changes in our urban development patterns: building smaller, more energy-efficient homes in areas close to jobs and public transit; allowing retail and services within walking or cycling distance of homes; and developing more robust non-car transportation networks that connect homes, workplaces, and other economic activity centers.
The Washington, D.C. metro area offers a useful lens on how development patterns over the past 30 years have impacted both climate concerns and housing affordability. The vast majority of new homes there have been built in low-density exurban or suburban counties—well outside existing public transportation networks. The fastest-growing communities are over 20 miles from the region’s primary employment center. Since 2010, multifamily housing forms an increasing share of new housing—a net benefit for climate impacts—but this shift reflects a sharp decline in the overall volume of housing construction, which worsens affordability concerns.
In this report, we analyze where the Washington, D.C., region has—and has not—built homes from 1990 through 2019, focusing particularly on proximity to public transit and jobs.
Public transportation and jobs in the Washington, D.C. region are highly centralized. New housing is not.
The spatial distribution of economic activity in the Washington, D.C. metro area follows a pattern typical of many older cities. Jobs are highly concentrated within 5 kilometers of the downtown central business district (CBD) and much less dense throughout suburban and exurban communities. The two largest suburbs, Fairfax County, Va., and Montgomery County, Md., are home to substantial job clusters as well.
The region’s Metrorail system is designed to facilitate traditional suburb-to-downtown commuting through a hub-and-spoke design (Figure 1). The District of Columbia has the most proximity to public transit (Metrorail and bus), as well as dense street networks with pedestrian and cycling infrastructure. The Metrorail network extends along two corridors in Montgomery County (northwest and northeast of the District) and to the west through Fairfax County; most of the land in these counties is not adjacent to high-frequency transit. Work is underway to extend Metrorail’s Silver Line to Dulles Airport in Loudoun County, Va.; these stations are projected to begin service in 2022.
Large employment centers and transit infrastructure are durable features of the built environment that persist for many decades. Therefore, a climate-friendly growth strategy for the region would concentrate new housing, retail, and services around these existing locations.
However, most of the region’s housing growth over the past 30 years has occurred in suburban and exurban areas, far from the CBD and in areas not well served by public transit. From 1990 until the Great Recession, fewer than 10% of all permitted housing units were in the urban core, compared to about 40% in suburbs and slightly more than half in exurban areas. The volume of new housing built in the region as a whole began declining in the early 2000s—well before the Great Recession. As of 2019, new home permits still lagged the pre-recession levels—an ominous sign for affordability.
Housing growth in the urban core has grown substantially since the early 2000s, with nearly 60% occurring in the District. Suburban jurisdictions have shown the slowest recovery following the Great Recession. Fairfax County—the largest jurisdiction in the region, with over 1 million residents—issued permits for more than 5,000 new housing units per year on average from 1992 to 2005, but has averaged fewer than 1,800 units per year from 2010 to 2019.
The exurban counties—notably Loudoun and Prince William counties in Virginia—saw explosive growth in the late 1990s and early 2000s followed by a sharp decline, and are just now reaching levels similar to the early 1990s.
The growing share of new development in the urban core is a net positive for climate resilience, because these jurisdictions have the highest density of jobs and the best access to non-car transportation. But the collapse of new housing in Fairfax and Montgomery counties leaves a large gap in the region’s overall supply. Investments in new Silver Line stations around Tysons Corner in Fairfax have spurred some localized housing development, but it’s well below overall production in the 1990s. Between 60% and 70% of new housing each decade was built in counties that have no Metrorail stations—a recipe for greater car dependence, longer commutes, and increased GHG emissions.
Exploring the underlying reasons why housing has or has not been built in specific counties is well beyond the scope of our analysis, but a simple exercise can rule out one hypothesis: The decline in housing growth is not due to lack of available land. During the 1990s and 2000s, new housing permits were negatively correlated with initial housing density—low-density communities built more housing. But that relationship has flipped in the 2010s, making housing growth positively correlated with density.
The District has the least amount of undeveloped land among metro area jurisdictions, and yet has increased production. Both Fairfax and Montgomery counties have ample amounts of open space, but have low-density development. Median home values in both counties are well over $500,000—an indicator of strong housing demand. The Washington, D.C. region’s trend toward concentrated housing growth in the dense urban core and stagnant supply in affluent suburbs mirrors other parts of the country.
The type of homes being built is also important for climate impacts. Single-family detached homes consume more resources for construction, maintenance, and operation than apartments in multifamily buildings.
As the location of housing growth has changed within the Washington, D.C. region, the composition of new development has shifted toward multifamily homes (defined as five or more units per building). From 1990 through 2005, roughly 25,000 single-family permits were issued each year, compared to about 7,500 multifamily units. From 2010 to 2019, single-family permits averaged around 12,000 per year, slightly more than the number of multifamily permits.
Throughout the period, a trivial number of permits were issued for duplexes, triplexes, and fourplexes—a point of interest for current discussions of zoning reforms to legalize these types of small apartment buildings in places where they are currently not allowed.
The shift toward a larger share of multifamily housing reflects primarily geographic changes in where new development occurred, as well as changes in the composition of housing within a few jurisdictions. Figure 6 shows the number of multifamily and single-family permits for the largest urban and exurban jurisdictions and the two largest suburbs. Nearly all the growth in housing permits in the District comes from apartments in multifamily buildings, while single-family production remained very small. Most newly built single-family homes in the urban core are teardowns that replace existing single-family homes, so do not represent a net increase in housing supply.
Loudoun County, on the other hand, has seen minimal growth in multifamily permits over time; changes in composition are due entirely to changes in the level of single-family permits. The two large suburbs, Fairfax and Montgomery counties, show notably different patterns: Fairfax County has seen a steady decrease in the level of both single- and multifamily permits, while single- and multifamily permits in Montgomery County have moved in opposite directions.
One housing characteristic that has important implications for climate impacts but which we cannot observe in our data is the amount of land used per housing unit (or lot sizes for single-family homes). The Census Bureau’s permit data groups single-family detached and attached (townhouse) structures together, and contains no information on lot sizes. Because townhouses use substantially less land per house than detached homes, a shift within the single-family category toward more townhouses could produce substantially greater housing density. Future analysis of new housing density using alternate data sources would be valuable.
The Washington, D.C. region’s housing growth over the past 30 years has mixed implications for climate impacts. Increased housing supply in the urban core (especially in the District) means that more households can live near the region’s largest concentration of jobs and have relatively good access to public transportation. Most new housing in the urban core is in multifamily buildings, which have a smaller per-household carbon footprint than single-family detached homes.
On the other hand, the continued rapid growth of single-family housing in exurban communities means that the majority of additional households in the region are locating in car-dependent places far away from job centers and living in carbon-intensive homes. And the overall decrease in the region’s housing production relative to the 1990s raises serious concerns about affordability. Housing prices have been rising faster than incomes, putting greater financial pressure on many households. Strong demand combined with insufficient supply are the perfect recipe for steeply rising housing costs.
Our analysis focuses on fairly large geographic areas—cities and counties—while other research finds considerable variation in housing growth patterns within individual jurisdictions. In the District, most housing growth was concentrated in a handful of neighborhoods, including moderate-income majority-Black neighborhoods such as Shaw and Brookland, or previously nonresidential areas such as NoMa and the Southwest Waterfront. Meanwhile the District’s most affluent, primarily white neighborhoods added almost no new housing.
The absence of development in job- and transit-rich centrally located neighborhoods throughout the District, Fairfax County, and Montgomery County reflects both formal regulations—low-density zoning and historic preservation—and the political clout of long-standing homeowners who organize to oppose change. These anti-growth efforts by affluent communities harm more than the physical environment; they also exacerbate long-standing economic and racial inequality and push low-income households into longer commutes from distant exurbs.
Data on housing permits was taken from the Census Bureau’s New Residential Construction Series. Information on the location of transit stations was drawn from the U.S. Department of Transportation. Dates of recessions were obtained from the St. Louis Federal Reserve Economic Data (FRED). Graphs of housing permits by year are shown as three-year rolling averages to reduce annual noise. Crosswalks between place and county census codes used the MABLE Geocorr application. Matching latitude-longitude coordinates for transit stations to counties used the Federal Communication Commission’s Block API.