Vanishing Automobile Update #36

How Much Open Space Is Left?

Report from the 2000 Census

Distributed 19 May 2003

A perennial argument for smart growth and compact urban development is that we are running out of open space. But how much open space is really left? Data now available from the 2000 Census show that at least 94.6 percent of the U.S. is rural open space.

The Census Bureau counts population and land area in a variety of categories:

Specific definitions of these and other census terms can be found in the Census Bureau's glossary.

More than two out of three Americans live in urbanized areas covering just 2 percent of the nation's land area. Counting urbanized areas and urban clusters together, nearly four out of five Americans live in urban setting that cover just 2.6 percent of the nation's land.

Remaining places account for just 4.4 percent of the U.S. population, but they cover 2.8 percent of the land. Obviously, their density is far lower than urbanized areas and urban clusters. The average urbanized area has nearly 2,700 people per square mile, and the average urban cluster has close to 1,500 people per square mile. But the average place (outside of urban areas) has just 133 people per square mile.

In many cases, this is because small towns have large corporate boundaries, only portions of which are occupied. This is most noticeable in Alaska, where many cities have legal boundaries that include thousands of square miles of unoccupied land. As a result, the density of Alaska's non-urban places averages just 7 per square mile.

Non-urban place densities in Arizona, California, Hawaii, Montana, Nevada, and Wyoming average between 30 and 100 people per square mile. In all other states except Nebraska, non-urban place densities range from 100 to 500 per square mile. Nebraska is the only state whose non-urban places approach urban densities: 805 people per square mile.

So are places "developed"? The Census Bureau counts them as "rural." Only people living in urbanized areas or urban clusters are counted as "urban." At the same time, a town of 1,000 people is obviously not "rural open space." Conservatively, only those areas outside of any "place" can be considered rural open space. But it is clear that large portions of the rural places are also rural open space.

Together, urbanized areas, urban clusters, and rural places occupy 5.4 percent of the nation's land, while urban areas alone cover just 2.6 percent. Rural open space thus covers something between 94.6 percent and 97.4 of the land.

On a state-by-state basis:

Although California is the nation's most populated state, it is hardly running out of land. More than 94 percent of Californians live in urban areas which cover just 5.1 percent of the state. When rural places are added, no more than 8.6 percent of the state is developed. Since California's rural places have an average density of just 93 people per square mile, most of their land area probably qualifies as rural open space. The nation's second-most populated state, Texas, is even less heavily developed: 2.7 percent urbanized and 5.0 percent developed.

Unfortunately, data from the 2000 census are not comparable with numbers from the 1990 census because the Census Bureau changed many of its definitions. Among other things, urbanized areas were redefined to exclude many undeveloped areas. This led, on average, to a 10-percent increase in population density of urbanized areas. Despite growing populations, the 2000 census reported many areas were smaller than measured by the 1990 census. The new data are probably more accurate, but it is hard to tell from them how fast land is being urbanized.

The American Dream Coalition web site includes a state-by-state comparison of these census results with the 1997 Natural Resources Inventory. You can also download an Excel file with complete data on land areas and populations of urbanized areas, clusters, rural places, and other rural land for every state.

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