By Fern Bromley
Urban sprawl—the expansion of cities typically due to a lack of planning or restrictions on spatial growth—is a quintessential part of the American landscape. According to economist Jan K. Brueckner, urban sprawl is enabled by three powerful forces: a growing population, rising incomes, and falling commuting costs. These three forces would encourage people to live farther apart from each other and distribute over vast spaces. A growing population can only spread out if it is affordable, incorporating the cost of commuting to the urban center. Urban sprawl can also be related to job sprawl, or the event of jobs popping up outside of dense urban centers. This can increase the amount of low income suburban communities which depend more on public transportation.
Apart from the socioeconomic problems created by urban sprawl, there are serious environmental consequences associated with the unbounded growth of cities. Despite recent drops in the number of people driving cars to work, population growth and increased commuting distances still increase air pollution and contribute to global climate change. Congestion requires cars to be on the road for even longer than necessary, exacerbating these issues. House construction across larger swaths of land increases land degradation, which drives habitat loss and decreases agricultural capacity. In cases where urban sprawl encroaches upon marshlands and other floodplain ecosystems, flooding can be intensified due to an increase in impermeable surfaces like asphalt and concrete. This contributed to the chaos following Hurricane Harvey in Houston, a city well known for its low density and far reach. Drastic and unprecedentedly large floods have also occurred in Mumbai.
Urban sprawl also leads to water pollution. Runoff on roadways can pick up gasoline and motor oil, while home maintenance also contributes. Fertilizers from lawns and pet waste can quickly build up and enter the water systems, affecting quality of drinking water and wildlife. This water pollution can become more than a local problem; for example, nutrient pollution from fertilizers in the Mississippi River delta is a long-term problem. Chemicals that are hazardous to aquatic species and/or humans flow into rivers when they are picked up by rain, and these pollutants can build up wherever the river ends up. Although large scale agricultural chemicals are the chief cause of this crisis, the multiple urban centers located along the 2,300 mile long Mississippi River and its suburban complements are key contributors.
There are legitimate concerns about life in today’s cities: there is more crime, less space, and less privacy. However, as cities grow, the expansive suburbs of today will become absorbed, and the urban areas will spread out more. From a social and environmental perspective, building on previously undeveloped land to create suburbs and ultimately allowing cities (and the cars, the polluters, that come with them) to swell boundlessly is not good planning.
Urban sprawl, as mentioned previously, is facilitated by three powerful forces: a growing population, rising incomes, and falling commuting costs. Theoretically, a policy that balances these three forces and encourages the development of distinct urban and rural areas could begin to solve many of the negative aspects of urban sprawl. Current high rates of population growth can be alleviated through many social policies, but from an urban planning perspective, encouraging density is key. Policies must also ensure that the housing within city centers would be affordable. Extensive and affordable public transportation systems, with cheaper commuting costs than driving a car, would alleviate air and water pollution. It also provides cheaper and more accessible transportation to low income communities.
Cities in the United States have acknowledged their sprawl and congestion problems through various means, achieving various level of success. New York City and the surrounding suburban areas are known for a vast public transportation system, with subways operating 24 hours a day and most buses running daily from 5AM–1AM. There are various commuter rail systems, including the Metro North Railroad servicing southern New York state and parts of Connecticut, the Long Island Railroad which stretches as far east as Montauk, New Jersey Transit, PATH, and Amtrak. Although the combined population of New York City and its suburbs exceeds the population of the city itself doubled, the city has contained its sprawl, making it the most populated and dense city in the country.
With the effects of climate change, land use, and excessive water consumption becoming more prominent and impactful with time, fixing urban sprawl across the United States could orient civilization towards a more sustainable future.
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