Metropolitan areas in the United

States are growing at unprecedented

rates, creating extensive urban landscapes. Many of the farmlands, wetlands, forests, and deserts that formed

the America of 1900 have been transformed during the past 100 years into

human settlements. Almost everyone

has seen these changes to their local

environment but without a clear

understanding of their impacts. It is

not until we study these landscapes

from a spatial perspective and the

time scale of decades that we can

begin to measure the changes that

have occurred and predict the impact

of changes to come.

The U.S. Geological Survey's (USGS)

Urban Dynamics Research (UDR)

program studies the landscape transformations that result from the growth

of metropolitan regions over time.

Using sources such as historic maps,

aerial photographs, and Landsat satellite data, USGS scientists first assemble retrospective urban land use databases that reflect several decades of

change. These databases are then used

to analyze the effects of urbanization

on the landscape, and to model urban

growth and land use change under

alternative growth scenarios.

Land Use Change

Most major metropolitan areas face

the growing problems of urban

sprawl, loss of natural vegetation and

open space, and a general decline in

the extent and connectivity of wetlands and wildlife habitat. The public

identifies with these problems when

they see residential and commercial

development replacing undeveloped

land around them. Urban growth rates

show no signs of slowing, especially

when viewed at the global scale, since

these problems can be generally

attributed to increasing population.

Cities have changed from small, isolated population centers to large, interconnected economic, physical, and

environmental features.

Urban growth and the concentration

of people in urban areas are creating

societal problems world-wide. One

hundred years ago, approximately 15

percent of the world's population was

living in urban areas. Today, the percentage is nearly 50 percent. In the

last 200 years, world population has

increased six times, stressing ecological and social systems. Over that same

time period, the urban population has

increased 100 times, concentrating

more people on less land even as the

total land devoted to urbanization

expands. Yet the temporal and spatial

dimensions of the land use changes

that shape urbanization are little

known, even in the United States.

In the United States, policymakers and

the public continue to raise concerns

about the effects that unchecked

urbanization has on the landscape. In

1998, more than 200 communities

across the Nation voted on, and the

vast majority adopted, measures to

manage urban sprawl. The UDR program provides basic data, predictions,

and perspectives to help in forming

sound policies for guiding environmentally sustainable growth.

Mapping Land Use Change

Databases developed by the UDR program contain interpretations of urban

extent, transportation routes, water

features, and other important land

uses. Selected regional studies are currently in progress across the Nation.

Data source availability for each

region, in conjunction with historical

significance, determines the time periods that are mapped. Features are

interpreted from diverse data sources

including historical topographic maps,

satellite images, census statistics, and

aerial photographs. The resulting temAnalyzing Land Use Change In Urban Environments

Nearly 80 percent of U.S. residents live in urban areas. This map, compiled from nighttime imagery acquired

by the Defense Meteorological Satellite Program, shows city lights for urban areas in red for the conterminous United States in 1995.

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 188-99

November 1999 Printed on recycled paper
poral database is a spatial record of

the pace and extent of the urbanization process. 

A temporal database can be visualized

as a sequence of maps, such as those

shown above and on the next pages,

or as computer animations. Sequential

maps show urbanization as a static

pattern that changes with each time

period that is mapped. Animations

illustrate the temporal dynamics,

revealing patterns and trends that are

not possible to discern from tabular

data or static maps. 

Understanding Land Use Change

The geographic understanding of land

use change in urban areas is a key

aspect of the UDR program. By analyzing a temporal database for spatial

patterns, rates of change, and trends,

the UDR program can provide insight

into how cities have developed under

varying social, economic, and environmental conditions.

This analysis requires understanding a

region's land use history. Population

data, timelines of historical events,

and related information are all used to

explain the mapped changes.

Population data are correlated with

the temporal database so that human

movement can be tracked and factored into these interpretations.

Population increases suggest economic growth and the availability of jobs

in an area, and population declines

suggest a decline in livability or economic issues that cause people to

leave a region. Timelines of past

events and other historical compilations aid in identifying the issues that

affected the development of the

region.

In addition to gathering statistical and

historical information, scientists must

have a physiographic understanding

of the place and its greater region.

Topographic features, climate, and

adequate supplies of water and other

natural resources can limit or encourage growth and change.

The existence and accessibility of

transportation routes have often dictated patterns of urban growth. Urban

areas that were established in the 18th

and early 19th centuries were usually

located along waterways, reflecting

dependence on shipping for the transport of goods and people. By the middle of the 19th century, railroads

began to connect existing towns and

spurred the growth of new urban

areas.

The post-World War II era saw not

only an increase in the population of

most metropolitan areas, but also the

emergence of a society dependent on

the automobile. The proliferation of

the private automobile led to expansive development at the edges of

many urban areas. The development

of the Interstate Highway system in

the 1950's spurred the widespread

construction of roads. As road networks expanded and became more

complex, urban development followed. As in the past, most recent

urban growth has occurred along

transportation corridors.

The UDR program provides the data

and geographic information necessary

to document past land use change. By

looking to the past, communities and

regions are better informed and

Portland

Vancouver

Portland

Vancouver

Portland

Vancouver

Portland

Vancouver

Portland

Vancouver

Portland

Vancouver

Salem

Salem Salem Salem

Salem Salem

Eugene

Eugene

Eugene Eugene

Eugene Eugene

Longview

Longview Longview Longview

Longview

This time series documents urban change in the Willamette Valley region over 115 years. The background in

each map is a shaded-relief image. The red areas represent urban extent for each time period. The Pacific

Ocean and the Columbia River are shown in blue. This study region extends from southern Washington south

to Eugene, OR. Within Oregon, politically defined urban growth boundaries have been in place since the

early 1970's in an attempt to control urban expansion.

This preliminary interpretation of urban land use

change for Chicago-Milwaukee shows urban growth

in 1955, 1975, and 1995. Each time period is represented by a different color. Black shows the extent

of urban growth in 1955, red represents 1975, and

yellow represents 1995.
equipped to plan and prepare for the

future.

Land Use Change Modeling

Historical land use patterns, together

with current trends in a region, are

used to model future land use.

Results from modeling urban growth

and land use change can be used by

the public, land use planners, and policy makers to anticipate and plan for

the future. Land use change models

can also generate alternative landscape predictions on the basis of different land use policies and environmental constraints.

These land use change models use

simple parameters including present

urban extent, major transportation

routes, topography, and protected

lands. Other factors, such as employment opportunities, land prices, and

the millions of personal decisions

people make, are not considered in

this modeling approach. The primary

focus of the modeling effort is to

account for physical controls on land

use. Acknowledging the uncertainties

of models, the USGS uses statistical

methods to predict probabilities of

urbanization.

Impacts of Land Use Change

Urban Dynamics research in landscape characterization, urban growth

models, and geographic understanding

provides the data necessary for analyzing the impacts of population

growth and land use change. This

information can be used to analyze

the causes of urban congestion, pollution, and loss of natural resources.

Each of these impacts is linked to

changes in the extent of urban, agricultural, and forested lands, and (or)

transportation systems.

Planners use Urban Dynamics data to

evaluate environmental impacts, to

delineate urban growth boundaries or

service areas, to develop land use zoning plans, and to gauge future infrastructure requirements. Traffic congestion, a common malady of urbanization, is the result of urban growth,

increases in population density, and

out-dated transportation infrastructure.

By evaluating trends associated with

land use change over time, solutions

to traffic congestion may be obtainable.

Another specific application of UDR

data is the correlation of air pollution

records with the temporal database to

determine if control strategies for

reducing pollution have been effective. Many pollution control strategies

have been used in the past three

decades. Correlation between land use

change and pollution helps

researchers establish positive or negative trends that indicate whether pollution control strategies have been

successful. With this information, policy makers, resource managers, and

the public can make appropriate

changes for the future.

Hydrologists can use Urban Dynamics

data to evaluate new water sources for

future urbanization and to analyze

water pollution – a problem common

to urban areas, industrial sites, and

agricultural lands. The amount and

degree of water pollution in rivers,

lakes, and bays can be predicted on

the basis of past and future trends in

land use change. A study currently

underway in the Patuxent River Basin

in Maryland focuses on the sources of

water pollution over time. In this

study, temporal change maps of

urban, agriculture, and forest lands are

used to identify and quantify historic

trends in sediment and nutrient loads

in waters draining into the

Chesapeake Bay. 

Geologists use data on land use

change to evaluate the availability of

building materials, such as sand, gravel, and cement. Geologists also use

data on existing hazards to correlate

with the UDR data to predict the

impacts of future natural disasters and

the potential damage they may cause.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

This series of maps shows more than 200 years of urban growth in and around the Washington, D.C. area.

The background in each map is a shaded-relief image. The red areas represent urban extent for each time

period and the blue is Chesapeake Bay. Projections for 2025, made with a land use change model, show

likely areas of new urban growth in yellow (high probability) and in greens (light green is moderate probability; dark green is low probability).
Policy makers can then use these

damage or hazard projections to direct

future development away from the

most at-risk areas. 

Finally, biologists also use land use

change data to compile maps on habitats, species distribution, and land

management. Predictions about future

urbanization are critical to the protection of ecosystems and the sustainability of communities. 

Products

The UDR program provides temporal

land use databases, analyses of land

use change, and landscape change

predictions. Databases for study sites

contain digital maps of urban extent,

transportation routes, water features,

and other significant land uses compatible for use in geographic information systems (GIS). Digital animations

are available to help visualize the

temporal patterns inherent in the data.

A land use change model and documentation are also available.

Interpretive papers and maps based on

the data and models are published in a

variety of formats. 

Study Sites

UDR projects are underway in the

metropolitan regions of Washington,

D.C., Baltimore, Chicago, Milwaukee,

Portland, Vancouver, New York,

Philadelphia, San Francisco, and Las

Vegas. Additional work is being done

in the Detroit River corridor,

California's Central Valley, the Front

Range corridor of Colorado, South

Florida, and in the Middle Rio Grande

Basin in New Mexico.

Collaboration

The UDR program is a joint activity

between the USGS and the University

of California, Santa Barbara. The

Baltimore-Washington study was also

supported by the University of

Maryland, Baltimore County, NASA's

Mission to Planet Earth, U.S. Census

Bureau, Library of Congress,

Smithsonian Institution, and Maryland

Historic Trust. We are actively seeking the participation of organizations

in new project areas as partners and

clients.

Information

For more information on the Urban

Dynamics Research program, please

contact

William Acevedo 

U.S. Geological Survey

Ames Research Center MS 242-4

Moffett Field, CA 94035

Phone: 650-604-5299

Fax: 650-604-4680

Email: urban@usgs.gov

Project descriptions, plans, and information generated by the program are

available at 

http://edcwww2.cr.usgs.gov/urban.

For information on other USGS products and services, call 1-888-ASKUSGS, use the ASK.USGS fax service, which is available 24-hours a

day at 703-648-4888, or visit the general interest publications web site on

mapping, geography, and related topics at

http://mapping.usgs.gov/www/products/mappubs.html.

Please visit the USGS home page at

http://www.usgs.gov/.

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

Washington D.C.

Baltimore

1850 1900 1953 1992

1850 1900 1953 1992

This series of maps compares changes in urban, agricultural, and forested lands in the Patuxent River watershed over the past 140 years. The top series shows the

extent of urban areas (red) along with agriculture (gold), which was at its peak in the mid-to late-1800s. Since 1900, the amount of agricultural land has declined as

urban and forested land (green) has increased.