Density – Shorthand for population density, or the number of residents per unit area, usually measured in number of residents per acre or square mile. Density is the mathematical inverse or opposite of land consumption per person (per capita). For example, a density of five persons or residents per acre equals 3,200 per square mile. This in turn equals a per capita land consumption of 0.2 acre per person

Developed Land – As defined by the U.S. Department of Agriculture’s Natural Resources Conservation Service in its National Resource Inventories, issued every five years since 1982, built-up or paved land that is at least one-quarter acre in area. Developed land can include built-up areas outside of urbanized areas, towns, or cities.

Foreign Born – Can be used as a noun or an adjective, describing a person born in a country other than the United States. Excludes those born abroad of American parents.

High-Density – A large number of residents per unit area, usually measured in terms of residents per acre or square mile. While there is no precise, agreed-upon criterion of high-density residential development, a density of approximately 5,000 per square mile would be considered relatively high-density.

Immigration – Permanent movement (i.e. settlement) of a foreign-born person to the United States under U.S. legal permission.

Immigrant Fertility – Fertility of foreign-born immigrants to the United States, usually expressed in terms of the Total Fertility Rate (TFR) of women, which is the average total number of children born to women of a defined group during the course of their reproductive years.

Low-Density – Relatively low population density, or low number of residents per unit area (acre or square mile). Urban / suburban densities of 1,000-2,000 per square mile would be considered low-density.

Native Born – A person born in the United States.

New Urbanism – A movement that sees urban centers as potentially vibrant communities that can mix and harmonize residential and commercial uses in clever ways to make cities satisfying and safe places to live and work. New urbanism supports such concepts as higher density in urban cores, mixed uses, mass transit, close proximity of dwellings to workplace, and others. New urbanism sees relentless sprawl in America as one consequence of the abandonment of our central cities.

Per Capita Sprawl – Sprawl that is driven by increase in per capita land consumption, that is, land consumption per resident, of an urbanized area, developed area, town, or city; per capita sprawl is measured in terms the increase in acres or square miles of developed or urbanized acres of land per person. Per capita sprawl and population-driven sprawl add up to 100 percent.

Population-driven Sprawl – Sprawl that is driven by increase in the population of an urbanized or developed area. Population-driven and per capita sprawl add up to 100 percent.

Population Growth – Increase in the number of residents of a given area, such as a town, city, urbanized area, state, or country over time. Population growth is equal to the total births of native-born residents minus the total deaths of native-born residents minus the emigration of native-born residents PLUS total immigration of the foreign born plus births to the foreign born minus deaths of the foreign born minus emigration of the foreign born (i.e. return to the country of their birth or a third country). In recent years, annual population growth in the United States as a whole has been running three million or more per year on average.

Rural Land – Undeveloped lands outside of urban areas, including farmland, pastureland, rangeland, and natural or semi-natural habitats, like forests, woodlands, wetlands, grasslands or prairie, and deserts. Rural lands may be flat or mountainous, and publicly or privately owned.

Smart Growth Movement – A loose, eclectic coalition of environmentalists, local growth-control activists, New Urbanists, municipal and regional planners, think-tanks, the federal government and many state governments, and even some home-builders united by their desire to slow the rate of sprawl.

Sprawl – As defined in this study, the increase in the physical area of a town or city over time, as undeveloped or rural land at its periphery is permanently converted to developed or urbanized land as population and/or per capita land consumption grow.

Urban Core – Used in this report as another description for "central location" as defined by the Census Bureau. The urban core is the entire city that anchors a metropolitan area, and usually is at its center.  It generally is the oldest, most densely populated and most built-up portion of an urbanized area. 

Urbanized Area – As defined by the U.S. Census Bureau, an area of contiguous census blocks or block groups with a population of at least 50,000 and an average population density of at least 1,000 residents per square mile.

Continue to Appendix B: Raw Data for 49 States (1982-1997)

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