Minnesotans For Sustainability©
Sustainable: A society that balances the environment, other life forms, and human interactions over an indefinite time period.
Sprawl in California
A report on quantifying the role of the state’s population boom*
Leon Kolankiewicz and Roy Beck
Table of Contents
While there has been scattered debate about whether rising consumption or population growth is primarily responsible for California’s urban sprawl, this study breaks new ground by actually attempting to quantify the role of each.
The study found that:
· California’s population boom has been the No. 1 factor in the state’s relentless urban sprawl, even though most anti-sprawl efforts exclusively target consumption factors.
· The supposedly gluttonous appetite of California citizens for more and more urban space per resident has in fact played little role in the sprawl. In most Urbanized Areas, land per resident did not grow at all – and it usually shrank in both the central city and in the suburbs. Thus, the average Californian was consuming land in an increasingly environmentally responsible way; but there were so many more Californians each year that sprawl marched ever outward.
· The volatile growth of California’s population far outweighed the sprawl effect of all other factors combined.
[The period of study was the most recent two decades for which comprehensive government data are available (1970-90).]
Why This Study Is Important
As governmental agencies, public officials, think tanks, corporations and advocacy groups devote more and more resources to taming California’s sprawl, the success of their efforts depends on their accurately assessing why the state’s sprawl occurs.
The authors embarked upon this study after a literature search found that media stories, advocacy programs, governmental reports and political statements about sprawl (1) have rarely stated that California’s population growth is a significant factor in sprawl and (2) have virtually ignored the possibility that slowing –or stopping– population growth might be an important tool in combating sprawl.
Thus, the finding by this study that population growth was the overwhelming factor in the state’s sprawl challenges the strategy of the anti-sprawl movement. And it points anti-sprawl advocates toward a new tool that if wielded successfully, would help their efforts to be more effective.
Effectively taming sprawl is of utmost importance to the future of California’s natural environment and human quality of life. For most urban Californians, continuing sprawl results in a direct personal cost of ever-worsening traffic congestion and gridlock. Aggravated traffic congestion alone has the potential to make Californians miserable enough to consider fleeing the state for some semblance of “greener pastures” in other less crowded western states. The greener pastures of Oregon, Washington and Colorado, and the brown deserts of Nevada and
Arizona, are rapidly being paved over to accommodate the crush of ex-Californians.
Inside California, the population build-up not only makes life more miserable for human residents but it is having a devastating effect on the state’s natural resources. The “ecological footprint” of each Californian includes not only the rural land on the edges of cities that gets urbanized but also far-removed rural lands and habitats that provide for each new Californian’s food, fiber, minerals, energy and other resources. Thus, the urban sprawl and spreading ecological footprints of millions of additional Californians have turned the state into one of the Earth’s “biodiversity hotspots.” That is, comparatively speaking, a very high fraction of the state’s unique and endemic plant and animal species – and the living communities and ecosystems they comprise –are imperiled by human activity and development associated with Californians’ vast numbers and colossal consumption.1
What Was Measured
Sprawl occurs when cities and suburbs expand beyond their boundaries and urbanize rural land at their edges. Each recent decade, California sprawl has degraded hundreds of square miles of some of the most scenic, fertile and biologically rich land in the country.
To determine how that has happened, the authors solely relied on the U.S. Bureau of Census’s painstaking calculations for each Urbanized Area of more than 50,000 residents. This is done only once a decade, a couple of years after the national census.
This study –a part of a larger national study that will be released later this year– examined the 28 Urbanized Areas in California for which there were at least 10 years of data. In each case, the study divided the overall sprawl between that which was related to growth in per capita land consumption and that which was related to population growth.
Per Capita Consumption Factors Can’t Explain Overall Sprawl
The study first checked to see if the data support the apparent assumption of most anti-sprawl efforts that per capita consumption factors are responsible for all or most sprawl. The combined effect of all urban planning, development, transportation, business and consumer decisions that influence consumption shows up in the statistic that tells us how much urban land is used on average for each resident. If that amount of land grows, a city has “Per Capita Sprawl.” A city can have no population growth at all, and still have considerable Overall Sprawl if the amount of land per resident is growing.
If Per Capita Sprawl were the sole factor in Overall Sprawl in California, the percentage growth of one would be the same for the other; for example, if per capita land consumption grew by 13%, total land consumption would also grow by 13%. Or if per capita land consumption growth were the overwhelming factor, its percentage growth would at least be close to that of Overall Sprawl.
· Not a single one of California’s 28 Urbanized Areas had a Per Capita Sprawl percentage that was even close to being as high as the Overall Sprawl percentage. On average, the older Urbanized Areas had no per capita consumption growth. Per capita land consumption actually declined by 8%.
· Despite that, the average older area sprawled (increased its total land area) by 60% over the two decades of study. [See Figure 1a.]
· The average new Urbanized Area also reduced the amount of land per resident (by 11%) while the total land area expanded by 40% over a single decade. [See Figure 1b.]
It is not that Smart Growth efforts are focused on the wrong factors but that many of them are focused too narrowly.
Obviously, there is another factor involved in sprawl, and that factor is population growth.
Sprawl and 28 California Urbanized Areas
When we compared population growth with growth in per capita land consumption in each Urbanized Area, we discovered the following:
· In 19 of the 28 Urbanized Areas of the state, growth in per capita land consumption did not appear to be related to any of the sprawl –because there was no growth in consumption by the average resident. It was population growth that propelled the sprawl.
· For example, average land consumption in the San Diego Urbanized Area fell from 0.203 acre (about one-fifth of an acre) to 0.188 acre (about one-sixth of an acre) per resident. But San Diego still devoured another 309.5 square miles of adjoining rural land as it added 1.1 million residents.
· Although residents of Palm Springs remained some of the largest urban land consumers in the nation, average land consumption plummeted from 0.607 acre in 1970 to 0.445 acre in 1990. Nonetheless, Palm Springs still sprawled by more than 40% ¾because of a burgeoning population.
· With no growth in per capita consumption, population growth was the factor related to 100% of the sprawl in those 19 Urbanized Areas.
· Included were small areas such as Chico, to medium ones such as Fresno, to large ones such as Riverside-San Bernardino. In every one of those 19, population growth outweighed all Smart Growth successes in reducing per capita land consumption.
· Population growth was associated with all of the 29% sprawl in Chico, all of the 68% sprawl in Fresno, and all of the nearly 50% sprawl in Riverside and San Bernardino.
· In 8 of the other Urbanized Areas, population growth was the dominant factor in the sprawl. In 27 of the 28 Urbanized Areas, population growth was related to more than two-thirds of the sprawl.
· Only in the Seaside-Monterey Urbanized Area did the some two dozen consumption factors combine to almost equal the influence of population growth in creating sprawl.
· Looking at the combined sprawl of all 28 of the California Urbanized Areas, the standard apportioning formula we used indicated that 95% of the sprawl was related to population growth.
· Only 5% of the sprawl was related to growth in the per capita land consumption which is the focus of nearly all anti-sprawl efforts.
That population growth is correlated with 100% of sprawl for so many California cities is a sign of some victory in the pursuit of the “densification” goals of conventional anti-sprawl efforts. It means that, for whatever reason, every one of those Urbanized Areas succeeded in stopping increases in per capita land consumption.
Of course, it is theoretically possible for a while to have population growth and no sprawl by forcing all new and old residents to remain within the confines of current urban land boundaries. But no American community anywhere has shown an inclination to do that.
Exhibit A of the limits to how far Americans
will go in cramming additional people into their neighborhoods is
Yet despite accepting the densest living conditions in the country, the Los Angeles area sprawled across another 394 square miles of orchards, farmland, natural habitat and other rural land. The reason? The addition of another 3.1 million residents.
California’s population growth is largely a function of federal immigration policies and national patterns of personal behavior, including fertility. Under current trends in federal policies and personal behavior, California is projected to rise from its current 35 million residents to just under 50 million in 2025. At that point, California will be as densely populated as China is now, and with no end in sight to rapid population growth.2
These population phenomena are shown by this study to be central to understanding the future of sprawl in California.
Nothing that has occurred in California’s cities thus far suggests that sprawl will not continue its march across California’s ever-more beleaguered rural and open spaces. In the process, the state’s environment and quality of life for residents will pay an ever-higher price for the nation’s unwillingness to stabilize its population.
This study has provided quantitative evidence in support of the common sense perception:
Population growth is a significant factor in California’s deplorable sprawl problem.
Studies and plans from state commissions,
think tanks, universities and advocacy groups that purport to offer blueprints
for combating sprawl without dealing with population growth look either naïve,
foolish or deceptive in light of the findings of this study.
Urban sprawl in California continues to destroy and threaten some of the most important ecological, agricultural and scenic land in the world.
In recent decades, the state’s urbanized areas burst outward in an explosion of sprawl that consumed countryside at a breakneck pace. Thousands of square miles of orchards, rangeland, farmland and natural habitats were covered by concrete, asphalt and the structures they underlie.
This has occurred at the same time California’s population has expanded from around 10 million in 1950, to 20 million in 1970, to 30 million in 1990, to 35 million in 2000, with no end in sight.
Were the two California phenomena –massive population growth and massive sprawl– related? Or was it primarily coincidental that they have occurred at the same time?
Coincidental, say many anti-sprawl enthusiasts. They argue that it is the increasingly gluttonous appetite of individual Californians for bigger houses, bigger lots, more cars, more parking lots and more roads that is the main culprit behind the sprawl.
Others argue that simple common sense suggests that population is a major factor in sprawl. After all, those new subdivisions spreading like wildfire across much of California are not being built just for the heck of it but to house more people –roughly half a million additional people each year and five million each decade.
1.1. Biodiversity hotspot
Regardless of the cause, urban sprawl has made California one of the Earth’s “biodiversity hotspots.” A frighteningly high fraction of the state’s unique and endemic plant and animal species –and the living communities and ecosystems they comprise– are imperiled by human activity and development associated with Californians’ vast numbers and colossal consumption.3
Despite some of the nation’s strongest efforts to tame sprawl, hundreds of additional square miles of the state’s rural land are churned under by the forces of urbanization each decade. The ecological as well as the quality-of-life future of California depends on efforts to protect the state’s land resources.
1.2. Anti-sprawl effectiveness depends on correct targeting
But to be effective, anti-sprawl efforts must be targeted at the factors that are most responsible for the encroachment on open spaces, natural habitats and farmland.
Approximately two dozen major factors have been suggested as culprits in sprawl:
· One factor is population growth.
· All the other factors combine to create growth in per capita land consumption –in other words, an increase in the average amount of urbanized land used by each resident of a city.
The relative contributions of the population factor and the combined consumption factors must be understood if anti-sprawl resources are to be used efficiently and effectively. And understanding is difficult without quantification.
The present report attempts to quantify the relative contributions of items (1) and (2) during the most recent 20-year period for which reliable and comprehensive data are available (1970-90).
1.3. No need for abstract debate
The authors embarked upon this study after a literature search found that media stories, advocacy programs and political statements about sprawl in the last few years have contained very few references to population growth as a significant factor. Nearly all public anti-sprawl efforts have been aimed at the factors that increase per capita land consumption.
Does growth in per capita land use explain virtually all of California’s sprawl, as conventional anti-sprawl efforts suggest? Or, rather, is population growth a significant –even dominant– factor?
While there has been little public discussion of this question, acrimonious debate has sometimes ensued when the question has been raised. Arguments on all sides have tended to involve either abstract assertions or non-contextual anecdotes.
This kind of debate is needless, for it is
quite possible to quantify the relative roles of population growth and of the
combined per capita consumption factors.
To begin this process of quantification, we must know what we are measuring when we speak of sprawl.
2.1. Quality vs. Quantity Measurements
Sprawl can be measured for both quality and quantity (amount). Measures for the quality of urban expansion include:
1) its low-density character, in contrast to compact urban cores;
2) its chaotic, or unplanned nature;
3) its dependence on the automobile; and
4) its connection with the decay of inner cities.
Overall Sprawl is the loss of rural land at the periphery of a city. This involves the conversion of open space or rural land into built-up, developed, or urbanized land over time, no matter the quality of that conversion.
We believe this measurement by amount most closely resembles the common American understanding of sprawl. If 25 square miles of open spaces around a city are urbanized, most Americans would consider that to be 25 square miles of sprawl, regardless of whether it was developed tastefully or not. They might be more offended by the sprawl if it included ugly development, but the amount of sprawl –and the number of rural acres lost– would be the same. Thus, using this measure, it is possible to have well-planned sprawl or chaotic sprawl, to have high-density or low-density sprawl, to have auto-dependent or mass-transit-oriented sprawl. But regardless of the quality of the sprawl, the amount of sprawl is measured by the square miles of rural land eliminated by urban development.
2.2. Census Bureau’s ‘Urbanized Areas’
Fortunately, it is easy to measure the amount of Overall Sprawl because of a painstaking process conducted by the U.S. Bureau of the Census for a half-century. Our study relies solely on Census data on Urbanized Areas of the United States to measure Overall Sprawl.4
The Census Bureau uses a rather complicated but consistent set of conditions to measure the spread of cities into surrounding rural land. The Bureau calls the contiguous developed land of the central city and its suburbs an “Urbanized Area.” It is possible to measure sprawl from decade to decade by noting the change in overall acreage of a specific Urbanized Area.
The Bureau introduced the Urbanized Area concept in the 1950 Census as part of its efforts to differentiate the urban and rural portions of the nation’s population. It recognized 405 Urbanized Areas in the United States as of the 1990 Census. [For further explanations of the Census Bureau’s methods in measuring Urbanized Areas, see Appendix B] Nearly every organization that addresses sprawl relies on these Urbanized Area data as the foundation of any
quantification of total sprawl. What they haven’t done is use those same data to quantify the relative roles of population growth and land consumption in generation of that sprawl.
As of 1990, there were 37 Urbanized Areas in California. Of those:
· 9 were designated for the first time in the 1990 Census. Prior to that, none of them met the Census Bureau’s minimum threshold of 50,000 population. Because they were not Urbanized Areas during previous censuses and thus had no previously quantified land mass for comparison purposes, they were not included in this study.
· 12 became Urbanized Areas in 1980, when they first had enough population to qualify. [We call these “new Urbanized Areas.”]
· 16 already were Urbanized Areas in 1970 at the beginning of the period examined by this study. [We call these “older Urbanized Areas.”]
2.3. Period of study
This study measures sprawl over the most recent two decades for which comprehensive government data are available (1970-90). But 12 of the 1980 Urbanized Areas were not large enough in 1970 to be counted as such. The data for those 12 cover only the 1980 to 1990 period.
Urbanized Area data are calculated only once
every 10 years. Thus, our study can assess the march of sprawl only through
1990. The calculations from the 2000 Census will not be available for a couple
of years, at which time we will update this report. Although it may be tempting
to try to estimate sprawl for the 1990s, the authors feel the Census Bureau’s
Urbanized Area data are so superior to all other sources that the use of other
sources to estimate sprawl would compromise the reliability of this study. An
exception would be a regular land survey by the Natural Resources Conservation Service of the U.S.
Department of Agriculture which is expected to report again in early 2001 for
development from 1992 through 1997. This survey
¾the National Resources Inventory¾
does not look at specific Urbanized Areas but surveys the conversion of
rural land into development throughout whole states, providing a useful
comparison for the urban-only data of the Census Bureau. We will include this
data in subsequent reports, including a forthcoming one that looks at sprawl
3.1. Many reasons for Per Capita Sprawl
Per capita urban land consumption is not limited to the size of a person’s house lot or to a person’s proportion of the land covered by an apartment complex. It also includes a portion of all the other land that has been converted from rural to urban use to provide for jobs, recreation and entertainment, shopping, parking, transportation, storage, government services, religious and cultural opportunities, waste handling, and education.
So the level of per capita land consumption is based both on direct individual decisions and behavior, and on collective decisions made through the government and the marketplace. The effect of all urban planning, development and transportation decisions shows up in the per capita land consumption figure.
In the end, per capita land consumption is calculated by dividing the total urban land area by the total number of residents. The resulting per capita figure provides a net result view of at least two dozen major factors that have been suggested as causes of consumption changes. [See Appendix C for more on calculating per capita land consumption.]
For several decades, per capita land consumption in most U.S. cities has been growing. At least two dozen factors have been advanced as being among the reasons more and more urban land is required for each resident.
The factors include:
· price of gasoline,
· inadequate urban planning and zoning,
· local and federal tax incentives and subsidies,
· crime and quality of schools in the central cities,
· mortgage interest tax deductions,
· racial and ethnic tensions,
· the Interstate Highway system and other transportation decisions,
· developer preferences,
· declining size of households caused by factors such as increased divorce rate, lowered marriage rate, later marriages, increased independence of young adults, increased longevity for women,
· consumer preferences for larger houses and yards, and
It is very difficult to measure precise
effects of trying to change each of the planning, consumption and other
behavioral factors mentioned above. But we can know the overall effect of all
those factors together by looking at the simple statistic of the average amount
of urban land per resident in an Urbanized Area.
The per capita consumption figure is a crucial gauge of the nature of sprawl in any Urbanized Area.
3.2. Per capita land consumption growth falls far short of total land growth percentage
When we look at Per Capita Sprawl figures for California’s cities, we find that –for whatever reasons– the goal of anti-sprawl programs to stop per capita growth has been substantially met. Most Urbanized Areas had no per capita consumption growth at all.
But Overall Sprawl in California’s Urbanized Areas continued at a raging pace –consuming more than 1,600 square miles of rural land during the period of study.
It appears that anti-Per Capita Sprawl efforts in California have been largely successful. But anti-Overall Sprawl efforts have been an abysmal failure. If Per Capita Sprawl were the sole cause of Overall Sprawl, the percentage growth would be the same for both. For example, if per capita land consumption grew by 38%, total land consumption would also grow by 38%. But in the Seaside-Monterrey Urbanized Area, per capita land consumption grew by 38% while the total land in the urban area grew by the far larger 97%. Where there was Per Capita Sprawl in California, it usually explained very little of the Overall Sprawl:
· The average older Urbanized Area had an 8% decrease in per capita land consumption but had Overall Sprawl of 60% (1970-90).
· The average new Urbanized Area had an 11% decrease in per capita land consumption but had Overall Sprawl of 40% (1980-90).
· Not a single one of California’s 28 Urbanized Areas had a Per Capita Sprawl percentage that was even close to the Overall Sprawl percentage.
These facts starkly reveal why nearly all Smart Growth efforts are failing –and will continue to fail– to stop sprawl as long as they focus virtually entirely on factors that cause per capita land consumption growth. It is not that Smart Growth efforts are focused on the wrong factors but that they are focused too narrowly.
Obviously, there is another factor involved
in sprawl. Without addressing that factor, Smart Growth programs as currently
envisioned are designed to fall short of protecting the agricultural land and
natural habitats surrounding cities.
For some reason, many otherwise intelligent observers seem to have a mental block that keeps them from understanding that the other factor in sprawl is population growth. The only factor that can make Overall Sprawl grow at a faster rate than the increase in per capita land consumption is population growth.
Despite the considerable complexity of sprawl in an urban area, nearly all of the complexity can be boiled down into what end up being two rather simple factors in an equation:
The amount of Overall Sprawl in an area is
equal to the change in per capita land consumption multiplied by the change in
population. In most American cities, growth has occurred in both factors.
* The Census Bureau classified these as Urbanized Areas
in 1970 or earlier.
We can learn a lot about the relative importance of each of these factors in California’s sprawl by lining up the growth percentages side by side. Fortunately, both the per capita land consumption change and the population change for each California Urbanized Area are readily available from the Census Bureau. An observer doesn’t have to be a mathematician to see that population growth has been a far greater factor in California’s Urbanized Areas than has been per capita land consumption growth.
In Tables 1a and 1b, we can compare the growth in the left column (population) with the growth in the middle column (per capita consumption) and see the huge disparity between the two in all but Seaside-Monterrey where the two factors contributing to Overall Sprawl are roughly equal.
When comparing the two growth factors, it
becomes apparent that any successful effort in
California to reduce the
percentage growth in the right column (Overall Sprawl) must place a major
emphasis on slowing population growth.
* The Census Bureau classified these as Urbanized Areas
But the population in the average older Urbanized Area grew by 78% over two decades. Population grew by 63% over a single decade in the average new area.
4.2. California's extraordinary population growth
The primary causes of population growth in a
state are (1) native increase [resulting from an excess of births over deaths
among natives and from domestic migration which is a net flow of people moving
from other states], and (2) immigration [new immigrants and an excess of births
over deaths among the foreign-born].
Since 1970, California’s population rushed past New York’s and even Canada’s and for many years expanded at an annual percentage rate that exceeded India’s.
In all California Urbanized Areas, sprawl has accompanied the increase in population. In most cases, the additional residents either require extra rural land for their urban needs, or they facilitate the movement of existing residents (e.g., by buying their houses) who then urbanize more rural land, or they create rapid demographic change which motivates existing residents to flee to the urban edges, converting rural land to accommodate their needs.
4.3 Population growth without sprawl still would enlarge ‘ecological footprint’
Few anti-sprawl efforts include suggestions for slowing or stopping California’s population growth as a way to control sprawl. When population growth is addressed, it usually is in the context that growth can continue without any urban sprawl if all additional residents are forced to live within existing urban boundaries, while preventing out-flight of the present population. This would mean that California city dwellers each year would have less and less land on average.
Nothing in the state’s political history suggests the ability or willingness to do this even for one year, let alone in perpetuity. But even if California’s citizens were to accept the escalating governmental regulations that would be required to handle each year’s population growth within existing boundaries, such a success would not ease the massive “ecological footprint” on the rest of the state.
It is important to recognize that the per capita land consumption figure upon which all conventional anti-sprawl efforts focus includes only the land consumed by an average resident inside his/her own Urbanized Area. It does not include all the rural land in other parts of California and other states that is required to obtain the food, fiber, minerals and energy for that resident, and to dispose of that resident’s wastes. The urban land is only a tiny fraction of the impact on the Earth that each new Californian makes. In fact, each person in an urban area has tentacles that extend far outward, pulling in natural resources from a variety of productive lands and waters of the biosphere.
Another way of expressing this is that every person has an “ecological footprint,” the area of biologically productive land he or she co-opts or exploits to satisfy the above-mentioned demands. The average American has an ecological footprint of 12.6 acres.6 This impacted area is roughly 25-70 times greater than the built-up space (i.e. developed or urbanized land) of one-sixth to one-half acre inside the California Urbanized Areas.
Thus, even if we were able to control urban
sprawl in the face of rapid population growth, the impact on the state’s
environment of rapidly growing numbers of Californians would still be enormous.
With percentages for the two overall growth factors available, it is possible to look at their ratio to each other to get an idea of their relative contribution to Overall Sprawl on a 100% scale.
This apportioning of “shares” of sprawl is an important tool for helping policy makers –and the people who elect or appoint them– know where to look for solutions. Over time, as sprawl spreads outward across the landscape, the shares of this expansion attributable to (1) increases in the average amount of land used by each resident and to (2) increase in population can be calculated.
We have used a standard mathematical methodology that is commonly applied to total consumption of various resources. Harvard physicist John Holdren –internationally honored in 2000 for his achievements in environmental science– has particularly developed, described and worked with this methodology.7 It can be applied to virtually any type of resource use. Perhaps its best-known application has been in understanding how total U.S. energy use has risen in recent decades. The apportioning formula has enabled analysts to apportion shares of the total increase to (1) the change in per capita energy use and to (2) the change in population.
The unique contribution of the present study
is that it appears to be the first to apply these methods to sprawl. As in the
case of looking at energy consumption, the question here was how much of the
increased total consumption of rural land (Overall Sprawl) was related to per
capita change in land consumption (Per Capita Sprawl) and how much was related
to the increase in number of land consumers (Population Growth). [See Appendix D
for further description.]
Please send mail to
firstname.lastname@example.org with questions or comments about this web site. Minnesotans For Sustainability
(MFS) is not
affiliated with any government body, private, or corporate entity.
Copyright © 2002 Minnesotans For Sustainability