Open Space and Smart Growth
The 10 sins of retail sprawl
It destroys the economic and environmental value of land
It encourages an inefficient land-use pattern that is very expensive to serve.
It fosters redundant competition between local governments, an economic war of tax incentives.
It forces costly infrastructure development at the edge of towns.
It causes disinvestment from established core commercial areas.
It requires the use of public tax support for revitalizing rundown core areas.
It degrades the visual, aesthetic character of local communities.
It lowers the value of other commercial and residential property, reducing public revenues.
It weakens the sense of place and community cohesiveness.
It masquerades as a form of economic development.
In communities across the nation, there is a growing concern that current development patterns -- dominated by what some call "sprawl" -- are no longer in the long-term interest of our cities, existing suburbs, small towns, rural communities, or wilderness areas. Though supportive of growth, communities are questioning the economic costs of abandoning infrastructure in the city, only to rebuild it further out. Spurring the smart growth movement are demographic shifts, a strong environmental ethic, increased fiscal concerns, and more nuanced views of growth. The result is both a new demand and a new opportunity for smart growth. For more information, visit Smart Growth Online
Long-term Relationship Between Development and Property Tax Bills
One of the long-term concerns about the tax implications of land conservation is that it prevents rather than encourages development, and development is presumed to lower municipal property taxes by adding to the tax base.
In general it is true that land increases in value when it is developed--thereby adding taxable value to the town's tax base. However, development usually requires more town services--thereby increasing the budget. Different types of development cost more in municipal services per dollar of tax revenue than others do. To investigate whether or not development leads to lower taxes, this study looked at the relationship between tax rates and the following indicators of development: population, employment, and business property.
Rather than taking a theoretical approach, this study documents what has actually happened to cities and towns in Massachusetts.
Population and Property Tax Bills
The most likely type of development a community will experience is residential development. In the past many people have argued that, in the long term, residential development helps to lower property taxes by increasing the tax base.
If this were true, it would follow that the Massachusetts towns with the most residents would have the lowest tax rates. Notably, this is not the case.
To examine the relationship between residential development and property tax rates, Massachusetts towns were ranked according to population and divided into five groups. The residential tax rate was then averaged for each group.
On average, the residential tax rate was lower in the group containing the towns with the fewest year-round residents and higher in the group containing the towns with the most year-round residents.
The most obvious explanation of is that, on average, residences do not pay enough in school taxes to cover the cost of educating the children in the residence. On average, according to the U. S. Census data, there were 0.45 school children per single family residence in Massachusetts in 1990. The average expenditure per pupil was $5,465 in 1996, meaning the average single family residence cost the average school district $2,459 to educate its 0.45 students for one year. The average single family residence paid $1,139 in school taxes, leaving a gap of $1,320 per year to be made up by other taxpayers, either through municipal property taxes or through state aid.7
Although more residences mean more taxes received by the municipality, they also mean more costs to the municipality.
This does not indicate that population growth necessarily means higher taxes; however, it does indicate that, on average, towns with more year-round residents have higher, rather than lower, tax rates.
Although more residences mean more taxes received by the municipality, they also mean more costs to the municipality.
This does not indicate that population growth necessarily means higher taxes; however, it does indicate that, on average, towns with more year-round residents have higher, rather than lower, tax rates.
Commercial Activity and Property Tax Bills
Recognizing that year-round residences are unlikely to pay their way, a second frequently asked question is: Wouldn't taxes be lower if the town had more commercial and industrial developments to pay property taxes?
It is frequently calculated that commercial and industrial developments pay more in taxes than they cost the town in services. The logical conclusion would be that towns with the most commercial and industrial tax base would have the lowest tax rates in the state. This is not the case.
Commercial and industrial developments pay both town and school taxes without directly increasing school costs. Most analyses of the fiscal impact of different types of development have found that, while year-round residences are a fiscal drain to the municipality, most nonresidential developments pay more in taxes than they cost the municipality to service.8 In addition, some towns in Massachusetts classify property to reduce the residential share of taxes and shift the tax burden to commercial and industrial property.
As a result, it would seem logical that towns with the most commercial and industrial activity would have the lowest tax rates. An analysis of the relationship between commercial development and tax rates indicates that this is not the case. On the contrary, average tax rates are generally higher in towns that have more commercial activity.
One indication of commercial activity is the number of jobs. To examine the relationship between property tax rates and employment, Massachusetts towns were ranked according to employment, and divided into five groups. The residential property tax rate was averaged for the group. On average, residential property tax rates were lower in the groups with fewer jobs and higher in the groups with more jobs.
Another indication of commercial activity is the value of business property. To examine the relationship between property tax rates and the value of business property, Massachusetts towns were ranked according to the total value of commercial property and industrial property and divided into five groups. The residential tax rate was averaged for each group.
According to this analysis, tax rates are not lower in towns with the most business property. On average, tax rates were lower in the groups with less business property, and higher in the groups with more business property.
This indicates that tax rates tend to be higher--rather than lower--in towns that have the most commercial activity. Similar studies in Connecticut, New Hampshire, Maine, and Vermont have found similar patterns: In general, average residential tax bills are higher in municipalities that have the most commercial and industrial development.9
On the surface, this finding seems to contradict both conventional wisdom and the fiscal impact studies cited previously that show that commercial and industrial developments are tax-positive. Several points should be considered in explanation:
* Commercial/industrial development and residential development go together. Municipalities that have commercial and industrial development generally have jobs. Residential growth, which costs more than it pays, accompanies jobs. Most fiscal impact analyses, when determining that a commercial development is tax-positive, do not consider these "secondary impacts." Although there are certainly examples of towns that have a disproportionate amount of commercial development, there is a very strong correlation between the number of jobs in town and the number of residents in the same town.
* In general, communities with larger tax bases offer more services. As mentioned earlier, larger communities often provide more services. In some cases, additional services are required to deal with the additional demands of growth and there is no net benefit to residents. In other cases, an additional level of service provides new or improved benefits to residents (such as 24-hour police protection or a municipal swimming pool).
* The charts show the relationship between total amounts of commercial development and tax bills. Clearly, a town would be better off if it could have a high proportion of tax-positive development and a low proportion of tax-negative development. This could happen, for example, if land and housing values were significantly higher in one town than in neighboring towns. If a commercial development were to occur in the town with high property values, it is likely that much of the associated residential development would occur in the surrounding towns where it would be cheaper to find housing. In that case, one town would get the tax-positive commercial development and the surrounding towns would get the associated tax-negative residential development.
Although there are certainly instances of towns receiving commercial tax base while the neighboring towns assumed responsibility for supporting the work force, in the long run it is likely that towns that get commercial development will also get at least some associated residential development.
* In general, commercial and industrial developments do not appreciate as rapidly as residential property or open land. A commercial development that represented 10 percent of the tax base initially may, over time, represent only 5 percent of the tax base--due only to differences in rates of appreciation.
* Massachusetts' state aid formulas tend to buffer the gains that might otherwise occur from a tax-positive commercial development. The formulas factor in growth in tax base and decrease state aid accordingly.
Although commercial and industrial developments generally pay more in taxes than they cost the town in services--at least directly and initially--the actual result in Massachusetts towns is that the tax rate is more likely to be higher--rather than lower--in towns that have the most commercial activity.
7. Census data from the Public Use Micro Data Sample for all Massachusetts Public Use Micro Data Sample Areas. Tax and expenditure data from the Division of Local Services. School taxes estimated as the same proportion of the property tax bill as school expenditures are of total local expenditures.
8. See, for example, Robert W. Burchell. 1992. Fiscal Impact Analysis and the Fiscal Impact Hierarchy: A Glimpse at the Argument. Prepared for the Lincoln Institute of Land Policy, Cambridge, MA. See also the Cost of Government Services reports prepared by the American Farmland Trust, Herrick Mill, No. 1 Short Street, Northampton, MA 01060. See also "Fiscal Impacts of Growth: Worksheets for Analyses." 1988. The Center for Economic Development, University of Massachusetts, Amherst.
9. This is documented in: Land Conservation and Local Property Taxes; Property Taxes and Development in the Squam Lakes Area; The Effect of Land Conservation on Property Tax Bills in Six Vermont Towns; The Effects of Development and Land Conservation on Property Taxes in Connecticut Towns; and Open Land, Development, Land Conservation in Maine's Organized Municipalities. All are available from Ad Hoc Associates, RD 1 Box 319, Salisbury, VT 05769.
TPL New England Region report, 1999
Create Range of Housing Opportunities and Choices
Providing quality housing for people of all income levels is an integral component in any smart growth strategy. Housing is a critical part of the way communities grow, as it is constitutes a significant share of new construction and development. More importantly, however, is also a key factor in determining households’ access to transportation, commuting patterns, access to services and education, and consumption of energy and other natural resources. By using smart growth approaches to create a wider range of housing choices, communities can mitigate the environmental costs of auto-dependent development, use their infrastructure resources more efficiently, ensure a better jobs-housing balance, and generate a strong foundation of support for neighborhood transit stops, commercial centers, and other services.
No single type of housing can serve the varied needs of today’s diverse households. Smart growth represents an opportunity for local communities to increase housing choice not only by modifying their land use patterns on newly-developed land, but also by increasing housing supply in existing neighborhoods and on land served by existing infrastructure. Integrating single- and multi-family structures in new housing developments can support a more diverse population and allow more equitable distribution of households of all income levels across the region. The addition of units -- through attached housing, accessory units, or conversion to multi-family dwellings -- to existing neighborhoods creates opportunities for communities to slowly increase density without radically changing the landscape. New housing construction can be an economic stimulus for existing commercial centers that are currently vibrant during the work day, but suffer from a lack of foot traffic and consumers in evenings or weekends. Most importantly, providing a range of housing choices allow all households to find their niche in a smart growth community – whether it is a garden apartment, a rowhouse, or a traditional suburban home – and accommodate growth at the same time.
Create Walkable Neighborhoods
Walkable communities are desirable places to live, work, learn, worship and play, and therefore a key component of smart growth. Their desirability comes from two factors. First, walkable communities locate within an easy and safe walk goods (such as housing, offices, and retail) and services (such as transportation, schools, libraries) that a community resident or employee needs on a regular basis. Second, by definition, walkable communities make pedestrian activity possible, thus expanding transportation options, and creating a streetscape that better serves a range of users -- pedestrians, bicyclists, transit riders, and automobiles. To foster walkability, communities must mix land uses and build compactly, and ensure safe and inviting pedestrian corridors.
Walkable communities are nothing new. Outside of the last half-century communities worldwide have created neighborhoods, communities, towns and cities premised on pedestrian access. Within the last fifty years public and private actions often present created obstacles to walkable communities. Conventional land use regulation often prohibits the mixing of land uses, thus lengthening trips and making walking a less viable alternative to other forms of travel. This regulatory bias against mixed-use development is reinforced by private financing policies that view mixed-use development as riskier than single-use development. Many communities -- particularly those that are dispersed and largely auto-dependent -- employ street and development design practices that reduce pedestrian activity.
As the personal and societal benefits of pedestrian friendly communities are realized – benefits which include lower transportation costs, greater social interaction, improved personal and environmental health, and expanded consumer choice -- many are calling upon the public and private sector to facilitate the development of walkable places. Land use and community design plays a pivotal role in encouraging pedestrian environments. By building places with multiple destinations within close proximity, where the streets and sidewalks balance all forms of transportation, communities have the basic framework for encouraging walkability.
Encourage Community and Stakeholder Collaboration
Growth can create great places to live, work and play -- if it responds to a community’s own sense of how and where it wants to grow. Communities have different needs and will emphasize some smart growth principles over others: those with robust economic growth may need to improve housing choices; others that have suffered from disinvestment may emphasize infill development; newer communities with separated uses may be looking for the sense of place provided by mixed-use town centers; and still others with poor air quality may seek relief by offering transportation choices. The common thread among all, however, is that the needs of every community and the programs to address them are best defined by the people who live and work there.
Citizen participation can be time-consuming, frustrating and expensive, but encouraging community and stakeholder collaboration can lead to creative, speedy resolution of development issues and greater community understanding of the importance of good planning and investment. Smart Growth plans and policies developed without strong citizen involvement will at best not have staying power; at worst, they will be used to create unhealthy, undesirable communities. When people feel left out of important decisions, they will be less likely to become engaged when tough decisions need to be made. Involving the community early and often in the planning process vastly improves public support for smart growth and often leads to innovative strategies that fit the unique needs of each community.
Foster Distinctive, Attractive Places with a Strong Sense of Place
Smart growth encourages communities to craft a vision and set standards for development and construction which respond to community values of architectural beauty and distinctiveness, as well as expanded choices in housing and transportation. It seeks to create interesting, unique communities which reflect the values and cultures of the people who reside there, and foster the types of physical environments which support a more cohesive community fabric. Smart growth promotes development which uses natural and man-made boundaries and landmarks to create a sense of defined neighborhoods, towns, and regions. It encourages the construction and preservation of buildings which prove to be assets to a community over time, not only because of the services provided within, but because of the unique contribution they make on the outside to the look and feel of a city.
Guided by a vision of how and where to grow, communities are able to identify and utilize opportunities to make new development conform to their standards of distinctiveness and beauty. Contrary to the current mode of development, smart growth ensures that the value of infill and greenfield development is determined as much by their accessibility (by car or other means) as their physical orientation to and relationship with other buildings and open space. By creating high-quality communities with architectural and natural elements that reflect the interests of all residents, there is a greater likelihood that buildings (and therefore entire neighborhoods) will retain their economic vitality and value over time. In so doing, the infrastructure and natural resources used to create these areas will provide residents with a distinctive and beautiful place that they can call “home” for generations to come.
Make Development Decisions Predictable, Fair and Cost Effective
For a community to be successful in implementing smart growth, it must be embraced by the private sector. Only private capital markets can supply the large amounts of money needed to meet the growing demand for smart growth developments. If investors, bankers, developers, builders and others do not earn a profit, few smart growth projects will be built. Fortunately, government can help make smart growth profitable to private investors and developers. Since the development industry is highly regulated, the value of property and the desirability of a place is largely affected by government investment in infrastructure and government regulation. Governments that make the right infrastructure and regulatory decisions will create fair, predictable and cost effective smart growth.
Despite regulatory and financial barriers, developers have been successful in creating examples of smart growth. The process to do so, however, requires them to get variances to the codes – often a time-consuming, and therefore costly, requirement. Expediting the approval process is of particular importance for developers, for whom the common mantra, “time is money” very aptly applies. The longer it takes to get approval for building, the longer the developer’s capital remains tied up in the land and not earning income. For smart growth to flourish, state and local governments must make an effort to make development decisions about smart growth more timely, cost-effective, and predictable for developers. By creating a fertile environment for innovative, pedestrian-oriented, mixed-use projects, government can provide leadership for smart growth that the private sector is sure to support.
Mix Land Uses
Smart growth supports the integration of mixed land uses into communities as a critical component of achieving better places to live. By putting uses in close proximity to one another, alternatives to driving, such as walking or biking, once again become viable. Mixed land uses also provides a more diverse and sizable population and commercial base for supporting viable public transit. It can enhance the vitality and perceived security of an area by increasing the number and attitude of people on the street. It helps streets, public spaces and pedestrian-oriented retail again become places where people meet, attracting pedestrians back onto the street and helping to revitalize community life.
Mixed land uses can convey substantial fiscal and economic benefits. Commercial uses in close proximity to residential areas are often reflected in higher property values, and therefore help raise local tax receipts. Businesses recognize the benefits associated with areas able to attract more people, as there is increased economic activity when there are more people in an area to shop. In today's service economy, communities find that by mixing land uses, they make their neighborhoods attractive to workers who increasingly balance quality of life criteria with salary to determine where they will settle. Smart growth provides a means for communities to alter the planning context which currently renders mixed land uses illegal in most of the country.
Preserve Open Space, Farmland, Natural Beauty and Critical Environmental Areas
Smart growth uses the term “open space” broadly to mean natural areas both in and surrounding localities that provide important community space, habitat for plants and animals, recreational opportunities, farm and ranch land (working lands), places of natural beauty and critical environmental areas (e.g. wetlands). Open space preservation supports smart growth goals by bolstering local economies, preserving critical environmental areas, improving our communities quality of life, and guiding new growth into existing communities.
There is growing political will to save the "open spaces" that Americans treasure. Voters in 2000 overwhelmingly approved ballot measures to fund open space protection efforts. The reasons for such support are varied and attributable to the benefits associated with open space protection. Protection of open space provides many fiscal benefits, including increasing local property value (thereby increasing property tax bases), providing tourism dollars, and decreases local tax increases (due to the savings of reducing the construction of new infrastructure). Management of the quality and supply of open space also ensures that prime farm and ranch lands are available, prevents flood damage, and provides a less expensive and natural alternative for providing clean drinking water.
The availability of open space also provides significant environmental quality and health benefits. Open space protects animal and plant habitat, places of natural beauty, and working lands by removing the development pressure and redirecting new growth to existing communities. Additionally, preservation of open space benefits the environment by combating air pollution, attenuating noise, controlling wind, providing erosion control, and moderating temperatures. Open space also protects surface and ground water resources by filtering trash, debris, and chemical pollutants before they enter a water system.
Provide a Variety of Transportation Choices
Providing people with more choices in housing, shopping, communities, and transportation is a key aim of smart growth. Communities are increasingly seeking these choices -- particularly a wider range of transportation options -- in an effort to improve beleaguered transportation systems. Traffic congestion is worsening across the country. Where in 1982 65 percent of travel occurred in uncongested conditions, by 1997 only 36 percent of peak travel occurred did so. In fact, according to the Texas Transportation Institute, congestion over the last several years has worsened in nearly every major metropolitan area in the United States.
In response, communities are beginning to implement new approaches to transportation planning, such as better coordinating land use and transportation; increasing the availability of high quality transit service; creating redundancy, resiliency and connectivity within their road networks; and ensuring connectivity between pedestrian, bike, transit, and road facilities. In short, they are coupling a multi-modal approach to transportation with supportive development patterns, to create a variety of transportation options.
Strengthen and Direct Development Towards Existing Communities
Smart growth directs development towards existing communities already served by infrastructure, seeking to utilize the resources that existing neighborhoods offer, and conserve open space and irreplacable natural resources on the urban fringe. Development in existing neighborhoods also represents an approach to growth that can be more cost-effective, and improves the quality of life for its residents. By encouraging development in existing communities, communities benefit from a stronger tax base, closer proximity of a range of jobs and services, increased efficiency of already developed land and infrastructure, reduced development pressure in edge areas thereby preserving more open space, and, in some cases, strengthening rural communities.
The ease of greenfield development remains an obstacle to encouraging more development in existing neighborhoods. Development on the fringe remains attractive to developers for its ease of access and construction, lower land costs, and potential for developers to assemble larger parcels. Typical zoning requirements in fringe areas are often easier to comply with, as there are often few existing building types that new construction must complement, and a relative absence of residents who may object to the inconvenience or disruption caused by new construction.
Nevertheless, developers and communities are recognizing the opportunities presented by infill development, as suggested not only by demographic shifts, but also in response to a growing awareness of the fiscal, environmental, and social costs of development focused disproportionately on the urban fringe. Journals that track real estate trends routinely cite the investment appeal of the “24-hour city” for empty nesters, young professionals, and others, and developers are beginning to respond. A 2001 report by Urban Land Institute on urban infill housing states that, in 1999, the increase in housing permit activity in cities relative to average annual figures from the preceding decade exceeded that of the suburbs, indicating that infill development is possible and profitable.
Take Advantage of Compact Building Design
Smart growth provides a means for communities to incorporate more compact building design as an alternative to conventional, land consumptive development. Compact building design suggests that communities be designed in a way which permits more open space to preserved, and that buildings can be constructed which make more efficient use of land and resources. By encouraging buildings to grow vertically rather than horizontally, and by incorporating structured rather than surface parking, for example, communities can reduce the footprint of new construction, and preserve more greenspace. Not only is this approach more efficient by requiring less land for construction. It also provides and protects more open, undeveloped land that would exist otherwise to absorb and filter rain water, reduce flooding and stormwater drainage needs, and lower the amount of pollution washing into our streams, rivers and lakes.
Compact building design is necessary to support wider transportation choices, and provides cost savings for localities. Communities seeking to encourage transit use to reduce air pollution and congestion recognize that minimum levels of density are required to make public transit networks viable. Local governments find that on a per-unit basis, it is cheaper to provide and maintain services like water, sewer, electricity, phone service and other utilities in more compact neighborhoods than in dispersed communities.
Research based on these developments has shown, for example, that well-designed, compact New Urbanist communities that include a variety of house sizes and types command a higher market value on a per square foot basis than do those in adjacent conventional suburban developments. Perhaps this is why increasing numbers of the development industry have been able to successfully integrate compact design into community building efforts. This despite current zoning practices – such as those that require minimum lot sizes, or prohibit multi-family or attached housing – and other barriers - community perceptions of “higher density” development, often preclude compact design.
Community Quality of Life
In 1989, the San Francisco Chronicle rated Suisun City, California, a town of 25,000 people midway between San Francisco and Sacramento, the worst place to live in the Bay Area. At that time, Suisun City's historic Main Street was a strip of boarded-up storefronts, vacant lots, and auto body shops. Several blocks away, an oil refinery sat at the head of the heavily polluted, silt-laden Suisun Channel. Today Suisun’s harbor is filled with boats and lined with small businesses. A train and bus station that connects the city to the rest of Northern California sits a few blocks away. The town is diverse, walkable, and picturesque. Its crime rate is low and its housing affordable.
How did Suisun City transform itself in a decade? Was it the beneficiary of a huge government redevelopment grant or a gift from a rich foundation? No such luck. Instead, Suisun City's residents, businesses, and elected officials agreed on a common vision for their town's future. Clean-up polluted Suisun Channel and make the waterfront a focal point of their town, they said. Re-establish historic Main Street as a social and retail gathering place. Strengthen municipal finances by encouraging tax-generating commercial development such as retail shops and restaurants along Main Street and the waterfront.
In its rebirth, Suisun City avoided large-scale redevelopment projects such as shopping centers and industrial parks that would have obliterated its historic, small-town character. Suisun City is still a work-in-progress. But this once-troubled town has turned the corner. Suisun City is invigorated with new businesses and residents, rekindled community spirit, and unbridled optimism about its future.
Growth and development can cut two ways. As the example of Suisun City illustrates growth can improve quality of life by adding services, creating opportunity, and enhancing access to amenities. It can also drive disinvestment, reduce competitiveness, and degrade the environment. Businesses, community leaders, developers, and local governments need to work to ensure that new growth improves the economy and environment of existing communities. In building places, communities must build places people want to live in for what they are, rather than for what they are not. This is smart growth.
By promoting the principles of green building design that combine energy and water efficiency, healthy indoor air quality and the use of natural building materials with mixed use neighborhoods, revitalized downtowns, walkable communities, and high density, low impact development, smart growth creates communities that provide environmental, economic, social and health benefits for all.
Recent trends in the global economy—industrial clustering and specialization, diversification of the workforce, reintegration of work and home—are placing a premium upon community character and quality of life. Companies are on the move and being drawn to communities that offer a good quality of life. Why? First, companies realize that their workers want to live in communities that offer reasonable commutes, a vibrant social life, environmental amenities, housing and transportation choice. To retain and attract their employees, companies must locate in such environments. Second, business is increasingly conducted beyond the boardroom—in cafes, restaurants, health clubs, public spaces, etc.—places where people can come together, converse, share ideas and network. The suburban office park, filled with buildings and cars, but with few destinations, is becoming an outmoded venue for conducting business. Lastly, the private sector in the new economy equates competitive advantage with the ability of being where the action is and to them the action is in urban or town centers. Although technology frees them to locate anywhere, it is proximity to suppliers, a workforce and networks that is drawing business to the central business district (CBD).
The emphasis on place presents enormous opportunities for communities to capitalize on their quality of life assets and to employ them as a tool for economic development. Doing so requires communities to think of quality of life as a commodity that can be cultivated and managed. Communities need to make strategic decisions that improve rather than harm livability and make them lucrative places for business, and labor to locate. The new economy values distinctive places that have the talent, technology and infrastructure to sustain competitive advantage. Talent is attracted to sociable communities—places with destinations, public and civic spaces, environmental amenities—where they can come together with colleagues and friends either through planned or chance encounters. Technological innovation is creating a wired society. Companies value offices and homes that are prewired to enable easy interaction between home and office. Aside from communication infrastructure, the new economy demands physical infrastructure that reduces the cost of business. This means buildings that can be quickly reconfigured and constructed, housing of varying types and costs, development patterns that are predictable, and transportation systems which increase mobility.
The prevalence of many of our current environmental challenges- air and water pollution; global warming, habitat fragmentation and conversion- is in part due to the way in which we have built our neighborhoods, communities and metropolitan areas during the past half-century- dispersed, inaccessible, and automobile oriented——in a word sprawling.
The farther we have to travel between home and work, work and play, the more likely it is that we will drive. Thus it should not be surprising that as the distances between trip origins and destinations has increased so has the amount of driving we have done. The end result of all of this driving is that the nation's air quality has suffered. Research has shown that compact, pedestrian and transit friendly communities have a positive impact on air quality by improving travel alternatives.
As we build, we replace our natural landscape——forests, wetlands, grasslands with streets parking lots, rooftops, and other impervious surfaces. The effect of this conversion is that stormwater, runoff which prior to development is filtered and captured by natural landscape, is trapped above impervious surfaces and accumulates and runs off into streams, lakes, and estuaries, picking up pollutants along the way. Runoff can be reduced through clustering of development, thereby leaving larger open spaces and buffers. Although compact development generates higher runoff and pollutant loads within a development, total runoff and pollutant loads are offset by reductions in surrounding undeveloped areas.
As development moves further and further to the metropolitan fringe it competes with open space habitat and prime farmland. Loss of open space impacts the environment in multiple ways. First, we lose many of the natural landscape features we value——forests, wetlands, etc. Second we lose the functions that these features provide——runoff control, wildlife migration, etc. And in the instance of farmland loss we hasten the use of lesser quality soils for production; thereby heightening conversion of forest and wetlands for crop production; and increasing dependency on irrigation, fertilizers and chemicals. Smart growth enables communities to pursue open space protection and development objectives through the clustering of development activity away from sensitive natural areas.
The way in which we design our communities directly impacts public health. Conventional community design, with its wide streets and absence of sidewalks, contributes to increased vehicle use and vehicle miles traveled (VMT)even for short trips. In the past 20 years, VMT has almost doubled and continues to increase faster than our population growth. In 1991, air pollution from highway VMT was estimated to have caused between 20,000 and 40,000 cases of respiratory illness. Most susceptible to respiratory illness are children. There has been a 160% increase in asthma in children under five years of age in the past 15 years. It is the leading cause of hospitalization for chronic diseases and of school absenteeism.
Growth patterns also affect the quality of the water we drink. Development activity results in the conversion of undeveloped land to impervious surface. This process reduces natural fillters such as wetlands, ultimately contributing to increased volumes of pollutants such as pesticides, fertilizers, and heavy metals in stormwater runoff. The threat to human health occurs when such runnoff enters a water body and ultimately into the drinking water supply.
Most communities today were designed to accommodate the automobile and do not have many sidewalks to facilitate walking and biking. These development patterns has ultimately ultimate caused sedentary behavior because of the reliance on the automobile and cost the public valuable opportunities to be physically active through walking and bicycling to school, work or for errands. Even more alarming, current growth patterns are causing a rise in obesity in both adults and children. Today, nearly one is four Americans is obese and 60 percent of Americans are overweight. Over the last three decades, the percentage of overweight children has doubled.
Smart growth is an integrative solution that addresses these trends and promotes a healthier, vibrant community. It helps reduce health threats from exposure to pollution and indoor contaminants, improves pedestrian safety, and engages residents and workers in a more active, healthy lifestyle. By promoting compact, walkable neighborhoods with mixed uses, walking and bicycling become viable transportation options.