Suburban sprawl, generally speaking, is the low-density expansion of cities over a wide geographical area, usually into undeveloped land. Single-use zoning, whereby residential and commercial areas are developed separately and without effort to make them accessible to each other is another characteristic of sprawling regions.
Wild habitats are destroyed as housing developments are built for people who seek larger homes and lots—at prices lower than they would find in the city— and more family-oriented neighborhoods in which to raise their children. Sprawl causes deforestation, land conversion from agriculture to asphalt (large parking lots are a prominent feature of sprawling suburban communities), air and water pollution, and inefficient transportation infrastructure reliant upon single passenger vehicles and long commutes. Indeed, according to city planners Andres Duany and Jeff Speck, “If the entire U.S. shared New York’s traffic death rate, we would save more than 25,000 lives per year.”
Urbanization and Sprawl
The rate of urbanization has been increasing over the past half-century. The global urban population rose from 745 million in 1950 (29 percent of the population) to 3.6 billion in 2011 (52 percent of the population). Many of these new urban residents end up living in the suburbs in developed countries, and in the suburbs and slums on the outskirts of town in developing countries.
Urbanization has not occurred evenly around the world. Urban populations are expanding at a faster rate in Africa, Asia, and Latin America than in industrialized regions. Demographers expect this trend to continue into the near future—the less developed countries will have an urban population of over 5 billion in 2050.
Urbanization can be a boon to population stabilization—just look at the extremely low fertility rates of the most urban places on earth (e.g. Singapore, Shanghai, Hong Kong). But when urbanization is paired with development that isn’t planned with sustainability in mind, sprawl is all too often the result.
Sprawl in the United States
Despite having replacement level fertility, the United States’ population is still growing by about 3 million people a year. Two-thirds of that increase is natural—it results from more births than deaths. We reached a milestone population of 300 million in 2006 and are hurtling toward a population of over 400 million by 2050.
Many facets of our everyday life will be affected if this demographic projection comes to pass. Housing prices will continue to rise to heights out of reach for many in the working middle class—pushing them farther into the suburbs; traffic and its accompanying air pollution will worsen; and wildlife habitats will shrink and degrade beyond the damage that has already occurred. Habitat loss affects not only the wildlife that once lived there, but also the people that rely on the crucial services provided by the natural environment. Natural areas provide many valuable resources that humans need to survive. For example, trees and wetlands are critical in protecting cities from floods, while also cleaning air and water by filtering out contaminants.
But population growth in and around cities does not have to create sprawl if cities are planned with sustainability in mind. Dense housing (apartments and condos instead of single family homes), ample affordable public transportation, and jobs near shopping and housing all lessen the effects of population growth on the rate of sprawl in a community.
Tysons Corner is currently a traffic-choked business and shopping area 14 miles west of Washington, DC. This “edge city” grew up around the 9th largest indoor mall in the U.S., a pattern recognizable in suburban communities around the country. The commercial district employs 120,000 people—it’s the 12th biggest employment center in the country—but currently houses only 17,000. “Every morning, 110,000 cars arrive, and they all leave at 5,” says Clark Tyler, chairman of Fairfax County’s Tysons Corner Land Use Task Force.
But all that is about to change because Tysons is getting a long-overdue makeover.
Beginning in 2013, a new Metro line extending from DC to Dulles Airport will stop in four Tysons locations along the way, bringing the subway system to the area for the first time. High-density housing with retail on the first floor is being built within a half-mile of these four Metro stops. New sidewalks and bike and pedestrian lanes will help expand transportation options beyond the single passenger vehicle.
The redevelopment project is the largest of its kind in the nation. Developers expect it to take decades to undo the damage of the past 50 years of bad planning, but without this drastic step the mess would just continue to get worse. Suburban sprawl may have been the predominant trend during the second half of 20th Century America, but high-density, walkable development may be the trend going forward.
In fact, the U.S. Census Bureau recently released figures showing that from 2010– 2011 population growth was higher in cities than in suburban regions, bucking a century-long trend toward higher suburban growth. More people are remaining in cities for employment and cultural opportunities. They have also delayed starting families, which is typically when young people move to the suburbs.
Sprawl in the Developing World
There are already around 1 billion people living in slums within and around urban areas, lacking access to secure housing, clean water, and sanitation. People’s quality of life is negatively affected as a steady stream of migrants crowds into the periphery of cities and competes with one another for space, resources, and livelihoods. And the rural-to-urban migrant stream grows stronger as population growth makes living in small villages more precarious.
Metro Manila—the urban conglomeration that includes Manila and the 15 cities surrounding the capital of the Philippines—is home to nearly 12 million people, 4 million of whom live in slums. However, the entire sprawling region is estimated to have over 20 million people, making it one of the largest megacities in the world.
The suburbs of Manila are growing rapidly, while the core city has barely grown in over 30 years. In fact, Manila proper now makes up only 8 percent of the urban area population; the inner suburbs make up 51 percent and the outer suburbs make up 41 percent. The population density declines markedly from the city (115,000 per square mile) to the inner suburbs (45,000 per square mile). The outer suburbs have 28,000 people per square mile—still quite dense by developed country standards (on par with New York City). The outer suburbs are now growing faster than the core and the inner suburbs combined.
The country’s population has grown rapidly since the 1960s, due largely to the fact that the Catholic Bishops’ Conference of the Philippines condemns family planning, making it very difficult for poor couples to access contraceptive services and supplies. Much of this population growth—from 26 million in 1960 to 95 million in 2011—has been absorbed by a spreading belt of land around Manila.
Single family homes and long commutes are becoming part of the suburban lifestyle in Manila, just as has happened in the more developed countries of the world. Housing developments have replaced rice paddies, hindering agricultural productivity. The incidence and severity of floods have increased due to the clearing of protective vegetative barriers. Traffic is infamous and air quality horrendous.
Suburban settlements in Nairobi, Kenya’s capital, are spreading into wildlife migratory corridors, with deadly results. The big cats that live in Nairobi National Park have started decimating the livestock of new arrivals from the countryside who live at the park bounds. These livestock losses end in the retaliative deaths of about 100 lions each year at the hands of angry herders.
Kibera is an infamous slum on the edge of Nairobi. It’s the largest slum in Africa and one of the largest in the world, containing 1 million people who share two public water pipes and one toilet for every 50 people. At any given time, about 50 percent of 16–25-year-old girls are pregnant. Only about 50 percent of Kibera’s residents are employed, mostly in unskilled labor.
Kigali, Rwanda needs 10,000 additional housing units every year, but fewer than 2,000 are constructed, leaving people to seek shelter in the overcrowded slums on the edges of the city. Developers are being urged by the Rwanda Housing Authority to build high-rise apartment buildings downtown to maximize the number of units on each small parcel of land.
Sprawl in Dakar, Senegal has forced people to live on marginal lands, where homesteading is risky. Floods have terrorized inhabitants of these areas in recent years.
Many of these African slum dwellers migrated from rural areas, hoping for a better life in the city. Whether they’ve found it is debatable.
Benefits of Population Stabilization
In the developing world, fertility decline in rural areas can help prevent the need for villagers to migrate to cities because they will be less likely to outstrip their natural resources (sabotaging livelihoods in the process). Unfortunately, many family planning programs do not have the financial and technical resources necessary to expand to rural areas. Taking the Rwanda example, the urban fertility rate is 3.4 children per woman, compared with 4.8 children in rural areas. Nearly one in five women has an unmet need for family planning—only 45 percent of married women are currently using a modern method of contraception. Unabated population growth due to unintended high fertility drives much of the urban congestion and suburban sprawl that we see in the developing world today.