For five years I lived in Baton Rouge, Louisiana. My house stood on a 0.63-acre lot in a residential neighborhood first developed in the 1950s. The name of the neighborhood, Magnolia Woods, is apt. Nature lovers seek homes there, particularly motivated by the lush canopy of trees. The lots are large enough to facilitate relatively high-functioning ecosystems. Birds abound, owls hooting from dusk until dawn. Frogs croak after each rain, accompanied by buzzing insects during the warmer months. Possums and raccoons rifle through the garbage when containers are not properly closed. Snakes slither from yard to yard, and coyotes even wander along the forested drainage watershed abutting the neighborhood (Dawson Creek), only six miles from downtown Baton Rouge. Dense, rich plant life and a wide range of tree species provide both food and shelter for animal inhabitants.
This wealth of urban biodiversity thrives primarily because the neighborhood is decidedly not a dense development. But Magnolia Woods could not be more different from most of modern-day residential developments expanding in the region. Magnolia Woods was constructed when residential developments were, for the most part, integrated into the existing ecosystem, as developers worked around slopes, trees, and other natural features. Now, common practice is to “high grade,” by removing all the vegetation on a series of lots, bringing in dirt to raise the level of the lots, grading them for optimal water flow, and cramming more houses onto less space—with an obligatory crape myrtle or live oak (or two, if you are lucky) thrown into a corner of the front yard and a postage stamp-sized backyard.
Indeed, closer to the Louisiana State University campus, along Burbank Road, a much denser series of residential developments are taking root. These houses and apartment buildings are packed tightly against each other on tiny lots. There is no room for meaningful tree cover. Fences fragment the landscape, leaving a dearth of species corridors and habitat linkages. The impervious rooftops and parking lots, combined with the limited pervious natural landscape, increase both flood risk in the region and negatively impact water quality due to nonpoint source water pollution. The area is just east of the levee running along the Mississippi River and comprises the watershed located between the levee and Highland Road. Prior to the construction of the levee, the Highland escarpment constituted the natural border of the Mississippi River floodplain—if residents did not want their houses to flood, they built them on the Highland Road ridge or beyond (there is a reason it was designated “high land,” after all). Now, thanks to the levee and perverse incentives created by the National Flood Insurance Program, the valley between the river and Highland Road is increasingly filled with dense residential (and other) developments. These developments have confoundingly ironic names like “Wildwood” and the “Woodlands,” despite the fact that impenetrable structures have replaced natural forests and wetlands that previously provided a host of ecosystem services critical to the community.
Many environmental and natural resource protection advocates support higher development densities. The idea is that by concentrating more development into less space, fewer resources are impacted and environmental quality is improved on a regional basis. In addition, having more dense developments in urban centers means that cities are (supposedly) less likely to sprawl outward. When one researches “urban sprawl,” low-density development (single-family homes on large lots) is often cited as a primary contributor. Reducing sprawl through dense development patterns theoretically leads to the consumption of fewer greenfield acres. It can also lead to fewer air pollutants, not the least of which is carbon dioxide. Many environmentalists, therefore, point to development density as one means of combatting climate change. Development density has the support of strange bedfellows, as residential developers also prefer dense development, for obvious reasons—developers can generate greater profits by squeezing more housing and other types of development onto the same amount of land.
From a natural resource management perspective, dense residential development may make sense in parts of the country where intense development occurs in location X and intense land preservation occurs in location Y. This is the point of policies like urban growth boundaries (whereby development density outside a certain boundary is reduced) and transferable development rights (TDRs) (whereby development occurs in one location in exchange for protection from development in other areas). Yet policies implementing dense development/intense preservation policies in tandem are largely absent from large parts of the country, like the southern United States. Southern state and local governments maintain some of the laxest land-use regulations in the nation. Dense sprawl results—that is, high-density development abutting high-density development abutting high-density development. This is especially problematic for the Southeast, one of the most ecologically rich regions of the nation, regarding its forests, wetlands, and biodiversity. Furthermore, even in areas of the country where land-use preservation policies are implemented more readily, like the Pacific Northwest, sprawl proceeds apace due to population growth (driven by both migration and immigration). So, absent more stringent growth controls and land preservation policies in some parts of the country, as well as reduced population pressures across the entire country, sprawl will continue. If residential sprawl is an inevitability, at least given the current orientation of immigration and land-use policy discussions across the nation, then society seems poised to make an important choice: to encourage sprawl to be dense, or, rather, to accept some sprawl additional to the status quo while integrating semi-functional ecosystems into residential (and other) developments.
The goal of this article is to challenge the prevailing conventional wisdom regarding residential development density. Where sprawl is proceeding unabated, and especially where it is proceeding most rapidly, advocates should consider the value of promoting less dense residential developments to allow more functional ecosystems to be integrated into human-impacted landscapes. This essay intentionally focuses on residential developments, such as single-family housing units, as other types of developments vary greatly with their economic and land-use policy drivers and the degree to which they may integrate open space. Ultimately, the trend throughout the last 40 or so years of cramming more residential units onto less acreage has damaged natural resource functionality in areas where those services are needed most. Indeed, what good are wetland ecosystem services such as flood control if there are no natural wetlands in urban areas prone to flood disasters? Given the backdrop of modern-day sprawl, resource sustainability advocates should reconsider whether high-development density is the optimal residential development strategy for protecting natural resources in certain regions.
The Problem of Sprawl in the United States
As detailed in two recent sprawl studies (hereafter referred to as the Vanishing Spaces and Measuring Sprawl reports), from 1982 to 2010, 65,000 square miles of undeveloped land were converted to urban development, 41 percent of which was forest, 27 percent cropland, and 29 percent pasture and rangeland. From 2002 to 2010, more than 13,000 square miles of natural resources were “cleared, scraped, filled, paved and built over.” Eighty-five percent of the land developed since 1982 is located on the edge of America’s most sprawling urban areas. See Leon Kolankiewicz, et al., Vanishing Open Spaces: Population Growth and Sprawl in America, NumbersUSA, Apr. 2014 (Vanishing Spaces), www.numbersusa.com/resource-download/vanishing-open-spaces; Reid Ewing and Shima Hamidi, Measuring Sprawl 2014, Smart Growth America (Measuring Sprawl), https://smartgrowthamerica.org/resources/measuring-sprawl-2014/.
What we call “urban sprawl” consists of two primary components. The first occurs due to population growth (population sprawl). The second component is sprawl associated with increases in the average amount of land developed per resident (per-capita sprawl). The combination of these two types of sprawl is what researchers call “overall sprawl.”
The 1990s brought about the most pronounced growth of overall sprawl in our nation’s history, and about half of total sprawl could be attributed to population growth and half to per-capita sprawl during that period. Over the last decade, however, 73 percent of sprawl has been driven by population growth. The Vanishing Spaces report is particularly critical of federal immigration policy, claiming that it has contributed to population sprawl. The United States has allowed one million immigrants to enter annually since 1990. After accounting for immigrant births, the United States adds a full 20 million new residents each decade. The Vanishing Spaces report acknowledges that movements like Smart Growth, LEED, New Urbanism, and similar programs are helpful for reducing per-capita sprawl, but the report also recognizes the limited utility of these movements in addressing overall sprawl, primarily due to its perpetuation by population growth. The report ultimately argues that unless the United States greatly reduces immigration, sprawl is inevitable.
Consider that areas of the country considered the gold standard of land-use planning—like Portland, Oregon—still witness new sprawl because of population growth. Portland is perhaps the iconic local government (and Oregon the iconic state) for modeling sustainability-driven land-use planning. Oregon requires all metro areas to have an urban growth boundary, and Portland has one of the most stringent. Yet between 2000 and 2010, Portland sprawled an additional 50.4 square miles notwithstanding its growth boundary policy, primarily because Portland added 266,760 additional residents during the decade. Even though Portland’s density increased, reducing its per-capita sprawl, it gained in population sprawl. Similarly, Raleigh, North Carolina, also became denser during the decade, but the addition of 300,000 residents caused it to sprawl outward an additional 198.5 square miles. Raleigh is in the Research Triangle, one of the most politically progressive regions in the southeastern United States. Portland is also politically progressive. One might think that land-use regulations would be utilized more effectively to halt sprawl in politically progressive regions. Yet in the face of population growth, in the absence of even stricter growth controls, and under current economic and political conditions, it appears that overall sprawl can only be slowed and not stopped.
The Problem of Density in the U.S. South
Drivers of urban population growth include immigrants entering the nation, as well as citizens migrating from one region of the nation to another. Both immigration and migration have contributed to a population boom in the South. Population and economic growth have increased more rapidly in the South than any other region of the United States, with urban areas expanding at the expense of southern forests and other natural resources. From 1970 to 2010, population in the South grew by 88 percent. From 1990 to 2008, population in the South grew at a rate approximately one-third faster than the nation, and growth of southern urban regions is expected to continue as population in the region grows yet another 40–60 percent from 2010 to 2060. David N. Wear & John G. Greis, U.S. Forest Serv., The Southern Forest Futures Project: Summary Report (2011), www.srs.fs.usda.gov/futures/reports/draft/summary_report.pdf.
Population growth is not the only driver of sprawl in the South, however, as it combines with regional political culture to exacerbate poor land-use planning. The South’s pervasive culture of lax land-use controls exacerbates per-capita sprawl, which, when combined with population sprawl, leads to overall sprawl greater than anywhere else in the country. Consider the rank of southern cities among the most sprawling regions of the United States. The United States’ most sprawling small metro area is Hickory, North Carolina; its most sprawling medium-sized metro area is Baton Rouge, Louisiana; and its most sprawling large metro area is Atlanta, Georgia. In fact, eight of the ten most sprawling metro areas nationally are in southern states, including seven of the top ten most sprawling large metro areas, the top ten most sprawling medium metro areas, and seven of the top ten most sprawling small metro areas. Of the 221 metro areas analyzed in the Smart Growth report, 38 of the 45 most sprawling regions in the United States are in the South. Measuring Sprawl, 19–20.
Most local governments in the South resist land-use controls, and particularly restrictions on density and environmental regulation. As Colin Woodward has argued, much of the South “continues to fight against expanded federal powers, taxes on capital and the wealthy, and environmental, labor, and consumer regulations.” Colin Woodard, Up in Arms, Tufts Magazine, Fall 2013. So not only is there resistance to federal “meddling” in state and local affairs, but even at the local level southerners are more resistant to regulatory restrictions on property rights notwithstanding environmental benefits that might accrue. This is particularly the case with land-use planning, where the cultural predilection to resist government regulation is paramount. Restrictions on land development are often viewed as the ultimate environmentally driven “command and control” governmental overreach. Making economic use of the land, after all, has long been a primary justification for the establishment and maintenance of property rights in the United States, and property rights advocates have become even more aggressive in defending economic development as a virtually inalienable right of property ownership. Furthermore, settlement patterns early in the nation’s history resulted in southerners defending and valuing individual liberty and property rights more aggressively than other regions of the nation. Effectively, Scotland’s honor-society-driven Highlander feuds were transferred to the southern United States. The totality of these circumstances creates a potent antiregulatory sentiment among southerners when it comes to limitations on property rights.
Unlike Oregon and Washington, most southern state governments leave land-use regulation entirely to local governments. The state of Tennessee purportedly requires municipalities to enact growth boundaries, but the policy seems primarily aimed at ensuring that growth occurs in the most economically efficient manner rather than protecting natural resources. A handful of prominent southern cities have growth boundaries as well, with Lexington, Kentucky, probably being the most effective from an environmental perspective. Other southern cities, such as Miami, Florida, seem preoccupied with guiding how land is inevitably developed rather than whether it should be developed or not.
While an Oregon model of land-use regulation would certainly be a step in the right direction for southern states, it, first, seems politically unlikely, and, second, may do little to retard overall sprawl driven by population growth. While better coordination across state and local governmental levels would be beneficial, state and local governments face a collective action problem. See Blake Hudson, Constitutions and the Commons: The Impact of Federal Governance on Local, National, and Global Resource Management (2014). To the extent that the federal government provides a coordinating function, most federal statutes implicating land use only address the symptoms of environmental problems, not the drivers of those problems. The federal Endangered Species Act aims to protect individual species but does little to address the habitat fragmentation that imperils species to begin with. The Clean Air Act regulates mobile source emissions but fails to address one of the primary contributors to mobile source pollution: land-use patterns that lead to more vehicle miles traveled to sprawling outlying regions in metro areas. The Clean Water Act fails to address the most significant threat to the nation’s waterways, nonpoint source water pollution, simply because it is considered the responsibility of state and local governments to implement land-use regulations.
Contending with the (Current) Inevitability of Sprawl
There appear to be three very different, though not mutually exclusive, options for addressing the seemingly inevitable threat that urban sprawl poses to natural resources in the United States, particularly natural resources in the U.S. South. The option chosen depends very much on the political will and culture of the locale in question. Political will and culture, in turn, vary greatly by region of the United States. As a result, advocates for land-use policies that more effectively address the harmful environmental effects of urban sprawl should prioritize options depending on the region of the country in which they will be implemented.
The first option is to enact land-use regulations that are far more stringent than those we see today in places like Portland, Oregon. Such policies would be more aggressive in requiring urban infill development, greatly restricting—or perhaps even prohibiting—greenfield residential developments. The goal would be to build up instead of out. Environmentally, this option could profoundly transform the landscape and improve the status of natural resources both within and outside of urban cores. Economically, however, this option would likely have high immediate costs, even if those costs are ultimately outweighed by economic and environmental gains later. Landowners outside the infill boundary would no doubt resist restrictions on the economic productivity of their land (and associated decreases in property values); residents would resist the potentially far higher costs of housing within the boundary (at least in the short term); and developers would push back against the much higher cost of redeveloping brownfields, to name only a few potential hurdles. While such hurdles do not render this option an inappropriate aspirational goal, politically this does not seem a viable policy choice anytime soon. Even though it might be the most effective at curbing urban sprawl, this option could very well lead to negative unintended social and economic consequences, at least absent countervailing adjustments in policy.
The second option is to allow dense development to occur wherever development pressures exist, even on greenfields, but to require that dense development be accompanied by dense protection of open spaces either on adjoining or outlying parcels. This has the benefit of not locking up all land from urban development, while allowing protection of natural resources on other lands in the vicinity. This appears to be the hope of environmentalists advocating for dense developments. It also seems to be the approach taken in parts of California, Oregon, Washington, and other states with more stringent land-use planning policies, such as environmentally oriented urban growth boundaries (though some otherwise effective policies, like King County Washington’s Critical Areas Ordinance—requiring 65 percent of a residential property to be left in a natural state—have been struck down on legal grounds. See Citizens’ Alliance for Property Rights v. Sims, 203 P.3d 378 (2009)). Yet in certain areas of the country, like the U.S. South, such policies are virtually nonexistent—at least on a scale that would have a significant conservation impact. The result is dense sprawl. Recall that developers are happy to align with environmental groups in advocating for dense development. The problem is that proportional protections of greenfields accompanying urban developments are lacking.
This leaves society with a third option. In the absence of more robust land-use restrictions on greenfield development or high-density/robust open space preservation policies, environmental and other advocacy groups should abandon a uniform “high residential development density is good” mind-set. Instead, they should advocate for less dense sprawl, calling for the integration of more open space into individual residential development projects. This may have the effect of mimicking per-capita sprawl, as more land is utilized per person. Yet, more functional ecosystems will remain in the spaces in between individual developments. In fact, not all per-capita sprawl is created equally. When society consumes more land per person by developing big box retailers, shopping centers, and associated parking lots, per-capita sprawl is clearly a negative for natural resources. In the context of less dense residential developments, however, per capita sprawl is not an inherent evil—even though more land is “developed” per person, much of that land is left as open space, allowing (at least) semi-functional ecosystems to exist. Perhaps what is lost in air quality/increased carbon emissions by sprawling further outward will be mitigated by gains in water quality, biodiversity protection, and forest preservation (and carbon sequestration). Not only should environmental advocates transition to this approach for the reasons outlined above, but also because it likely will be more politically viable than the other two options in locations like the southeastern United States. Though southeastern state and local governments are already reticent to implement stringent land-use policies, this option is the least invasive of the three into individual property rights. Under this option, no property is off limits for development (absent other applicable legal restrictions, of course). Rather, individual development projects merely must be less dense. Although there may be no urban growth boundaries outside of which a developer would be restricted in placing residential developments, the developer would be limited to placing 200 houses on 100 acres of land instead of 300 houses. This option is more a matter of degree of development as opposed to the more controversial question of whether development may occur.
Less dense residential developments provide several environmental and political benefits (though some of these also apply to option two). First, ecosystem services are retained in locations where they are most needed. Larger residential lots improve water quality and better facilitate groundwater recharge because impervious surface cover is reduced. For the same reason, they also aid in flood control. Floods are only a problem because they affect people. Controlling floods where people are located is what is most important. Residential urban areas are where these ecosystem services should be promoted, and larger residential lots help achieve that. Less dense residential areas also allow for more tree cover, which reduces the urban heat island effect and increases air quality, as trees capture particulates and other forms of air pollution. Less density also will more effectively provide wildlife corridors and ecosystem space (in trees and other areas) for insect, amphibian, and other species to thrive.
Second, less dense developments should protect a wider sampling of ecosystem and species types rather than targeting large swaths of ecosystems to destroy with density while protecting other ecosystem types in outlying areas. Consider a location like Houston, Texas. Situated near the dividing line between the eastern and western United States, Houston sits at a cross-section of ecosystem types—from southern pine forest, to coastal, to plains, to desert. These ecosystems are populated by different species of plants and animals. By reducing density to better integrate these plants and animals into the environment, rather than eradicating them through dense sprawl and then preserving (or not) ecosystems elsewhere, a wider sample of ecosystems, both functionally and geographically, may be preserved, at least in part.
Third, less dense developments force developers to internalize more of the externalities caused by their development, something that most other polluting industries must do. The problem seems to be that society does not look at urban sprawl as pollution, but rather considers it economic progress. Yet, sprawl is a primary contributor to environmental degradation, whether it be increased water and air pollution, loss of biodiversity, an increased urban heat island effect, or other harms. Developers of dense developments receive 100 percent of the gain from cramming as many residences as they can on less acreage, while society bears the cost and suffers the incremental and aggregated harms of losing open space to increasingly impervious surface cover. By requiring reduced development density, developers internalize at least some of the externalities they create by facilitating better integration of ecosystem services into developments.
Fourth and finally (in a nonexhaustive list), less dense residential developments can tap into the psychology of consumers to stimulate demand for the less dense residential development product. It appears consumers have accepted the shifting baseline toward more dense developments, seemingly without missing the amenities that more lushly vegetated neighborhoods can provide. But unlike commercial developments, where people are not necessarily motivated to shop in a location because of the amount of green space on the premises, people do fundamentally support having natural resource amenities where they live. Poll after poll has shown that people generally want access to environmental amenities. See, e.g., Pennsylvania Land Trust Ass’n., National Poll Results: How Americans View Conservation, ConservationTool.org, http://conservationtools.org/guides/111-poll-results. The problem has been that the supply is limited. I often ask students who have visited Hilton Head Island, South Carolina, what they think about the town. They respond that it is beautiful. They also respond that it is expensive. This is a supply-and-demand problem. There are not enough nice, low-density developments like Hilton Head, especially in the southeastern United States, and so these places are more expensive to visit. More people demand to visit locations like this than are supplied by southeastern land-use policies. By requiring lower-density residential developments, policy makers may be providing consumers with more of something that they really want, while making it more affordable.
Better Integrating Environmental Systems into Living Spaces
This article is not an empirically driven dissertation nor is it meant to be an assault on the benefits of development density. Rather it is intended as a thought experiment about how we can better integrate environmental systems into the places where we live. It is motivated by frustration at how we have moved toward a residential development system that squeezes evermore greenery and natural resources out of individual developments and replaces them with concrete and rooftops. If sprawl is inevitable, and in the absence of political will to take more stringent measures to protect natural resources within and surrounding urban areas, we should consider another approach—make sprawl less dense. Bring the actual environment back into the residential environments where we spend so much of our lives.