Urban Sprawl

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Urban Sprawl

What is Sprawl?

The term sprawl was first introduced in 1937 by one of the first city planners in the southern United States, Earle Draperone. Sprawl is defined as the “tendency toward lower city densities as city footprints expand.” In more specific terms, the term urban sprawl as used in the pattern of land development in the United States as “spread-out” or “unlimited and noncontiguous way outward” with “one- or two-story single-family residential development on lots ranging from one-third to one acre (less on the West Coast) accompanied by strip commercial centers and industrial parks, also two stories or less in height and with a similar amount of land taking.”

Historical Perspective

When the industrial revolution transformed the United States from an agrarian based economy to a market dominated by industry and manufacturing, cities became the dominant type of settlements. In 1790 approximately five percent of the entire population of the United States lived in areas termed “urban.” However, this figured tripled to fifteen percent by 1850 and continues to increase today. In fact, figures from the 2000 Census documents almost eighty percent of all Americans indicating that they live in urban areas.

When the 1950 Census began separating central city population and those who lived in suburban areas, data which could be used to document urban sprawl became available. The data from this date (1950) show the evolution of cities and the growth and densities within both the central cities and the suburban areas. In particular, the data demonstrates that central cities have a relatively stagnant growth rates in both population and land area. On the other hand, suburban areas have experienced a large increase in the rate of growth of both. In fact the evidence shows :

Approximately 65 percent of the urbanized population lived in central cities in 1950, with the :remaining 35 percent residing in suburbs. By 1990, these percentages had flipped, with central city :populations down to 35 percent of populations within these urbanized areas. The total land occupied :by central cities has fallen from roughly 40 percent to 20 percent of urbanized areas during the :same time.

At the same time, the densities of the population in both central cities and suburban areas have displayed a steady drop elucidating to an expanding city footprint, or in other terms urban sprawl. Today, sprawl is an ever present phenomenon that occurs in not only the United States, but worldwide. Countries in Western and Eastern Europe, Latin American, as well as some parts of Asia all have experienced an increase in their cities’ footprints. Specifically, the United States experiences sprawl that is predominantly residential in form (low-density residential developments in rural and undeveloped areas).

Ecnomic Forces and Urban Sprawl

The "monocentric city model" (Alonso, 1964; Muth, 1969; Mills, 1967) describes the basic urban structure as being a fundamental result of the trade-off between commuting costs and land rents per acre. This model, when in equilibrium, acknowledges that higher commuting costs (as you move farther away from the central business district (CBD)) result in lower land rents per acre which offset this increasing cost. As the rent decreases, the opportunity cost of purchasing more land declines and more individuals purchase larger plots of lands or houses, decreasing density levels. More specifically, this model can be analyzed as an individual or group commutes to their place of work, earning (y) income and incurring a commuting cost of (t) dollars. If then, they commute a total distance of (x) miles, total disposable income would be equivalent to y - t(x). Because commuting costs would necessarily increase as the distance from the CBD increases (as (x) increases so do total commuting costs), land rents per acre (r) must necessarily decrease. Due to this fact, people substitute away from non-housing goods (c) and toward larger land plots or bigger houses (q). However, the level of land consumption and average land rent per acre is also dependent on other variables. Commonly, these variables can be seen as written: r(x,y,t,u) and q(x,y,t,u) with (u) equating the common utility level enjoyed by city residents. This urban utility comes from two separate equilibrium conditions. (1) a city must fit its population and (2) urban residents must purchase land from farmers or at least outbid them for the land. When these two conditions are implemented and analyzed using within this model it can be seen that a city's footprint will increase in size as the population increases or as an individual's income increases. On the other hand, if the commuting cost or agricultural land rent increases the size of the city's footprint will fall.

Looking at the rapid population growth experienced in the United States, the increase in per captia GDP, and the technological innovations that have decreased commuting costs it can be seen that these features have caused massive expansion of cities throughout the USA resulting in many instances urban sprawl.

Market Failure Leading to Excessive Urban Growth

It has been documented that there are three potential market failures that have been attributed to an increase in a city's footprint. These failures are considered externalities which are not internalized.

(1) TRAFFIC CONGESTION AND SPRAWL

Results indicate that the increase in traffic congestion as a result a city's increased spatial size costs on average almost 70 billion dollars a year, or approximately 520 extra dollars per person. Primarily, this loss of income is a result of the additional increase in time spent commuting and higher levels of fuel consumption. The increase in traffic congestion must also account for the addition levels of air pollution which come as a direct result of the increase in emissions due to the larger population of vehicles on the road as well as the increase in the distance spent commuting. Empirical analysis has shown that between 1970 and 2001, total miles traveled by passenger vehicles has increased from 920 billion miles to over 1.6 trillion miles per year.

HOWEVER, the link between sprawl and traffic congestion and the resulting pollution is somewhat unclear. If it is the case that edge cities are more prevalent in an area, the miles spent commuting could actually be diminishing or at least less than the national average as jobs become less centralized in the CBD and more sporadically placed. Similarly, the levels of air pollution in the United States has steadily declined since 1970, most likely due to the fact that technology improved the type of vehicles on the road and replaced the older, high pollution causing automobiles.