Full-resolution NORM ED image of Sioux 

1,020-m cells, the unit of averaging for th

and in some places climate (northern Applications Environmental Assessment 

Among these are 

concentration of natural drainage, production of dust, introduction of 

Roads al

Distance to Nearest Road in the Conterminous United States 

NORM-ED 1-km resolution image of southern Louisiana. Baton Rouge is the yellow patch in the northwest corner and New Orleans 

Lakes 

Pontchartrain and Maurepas form the large green patch north of New Orleans, interrupted by only two roads. The Mississippi Delta extends to the southeast. The barrier islands stretching northeast and southwest from the delta are some of the places most remote from roads in the conterminous United States. Other green areas are nearly roadless coastal swamps. 

U.S. Geological Survey 

Fact Sheet 2005-3011 

January 2005 

A New Dataset 

Monitoring (GAM) program has conterminous 48 states. and intensity of road construction. This indicator measures straight-line or Euclidean distance (ED) to the nearest NORM ED. NORM ED data can be for The National Map, 

The 

fullresolution dataset for the conterminous 

The North American Road Network Overview on Earth. It consists of more than 4 

The documented 

approximately 1% of the land area of the United States, roughly the area of South Carolina. 

Roads are the circulatory system of our 

culture. processed goods, and to carry people to friends. and use. 

Spatial 

descriptions of the association of roads with their surroundings. NORM ED, in roads. 

The National Distance to Road Image Properties of the Image 

The background on this page is an 

road (DTR) for cells measuring 1,020 m (0.63 miles, nominally 1 km) on each side; 7.5 million 1-km cells are displayed. Each full-resolution 30-m dataset. The same on page 2. 

Patterns of Open Space and Road Density 

The northern of 

the city of Rio Rancho. road density) is colored blue. These conditions typically occur in areas where making land highly accessible. Blue areas occur in all states, and are particularly prominent across the Great Plains; along and to the west of the Cascade Mountains in this DTR range. represented in shades of blue-green or turquoise. turquoise (ridges). California. lacking. population. 

Shades of green represent areas remote 

from roads. Most of these occur because 

Steep slopes 

visible outside the city. Interstate 90 runs 

(Rocky Mountains, Sierra Nevada), swamps (southern Florida and LouisianMaine and Minnesota), have made road building difficult and expensive. Many these places are preserved as National Parks (Yellowstone, Everglades) and Wilderness Areas. Nationally, these roadless areas are scarce, and they occupreferentially in the West. Roads and traffic affect natural resourcein dozens of ways. elimination of forest canopy, elevation otemperature, introduction of vehicular noise and pollution, diversion and invasive species, and collision of vehiclwith animals large and small. serve as the primary mechanism for conveyance of humans into the landscap

the yellow patch in the center. 

U.S. Department of the Interior 

The USGS Geographic Analysis and 

developed a national, high resolution dataset that gives the distance to the nearest road every 30 meters across the 

This work 

provides the first unified national picture of roadless space, vehicular accessibility, 

The new dataset is the first member of 

the National Overview Road Metrics (NORM) family of road related indicators. road, and is given the compound name viewed and downloaded from the transportation section of the web viewer http://nationalmap.usgs.gov. states is made up of 8.7 billion values. 

The road network of the United States 

is one of the largest human constructions million miles of mapped roads, plus many additional utility roads, 4-wheel-drive trails, and private routes. roads and their rights-of-way occupy 

They are used to bring raw 

materials to processing sites, to distribute their schools, workplaces, jobs, and 

The value of roads is reflected in 

the significant size of the economic sectors—energy, automotive manufacturing, mining, and construction, among others—that support their building 

The U.S. road network is little studied 

as an integrated object. relationships between the network and 

intervening roadless areas are important to ecological and hydrological resources. The NORM indicators provide basic particular, focuses not on the characteristics of the road network itself, but rather on the extent of spaces between 

image of average values of distance to cell averages 1,156 DTR values from the image is reproduced in more vivid color 

Areas of lowest distance to road 

(highest road density) appear in yellow. Most low DTR areas are in cities, but there are exceptions. For example, energy extraction activities have developed dense road networks in the oil and gas fields of West Texas and the Texas Panhandle; these appear as yellow arcs. two adjacent bright yellow areas in north central New Mexico is the product of road construction in advance of settlement in 

Moderately low DTR (moderately high 

terrain and vegetation are not impediments to road building, and where there is motivation—such as agriculture—for the Snake River Plain in Idaho; in the Central and Imperial Valleys of California; in the Pacific Northwest. The Atlantic Seaboard, outside of its many cities, falls 

High DTR (low road density) is 

The alternating valleys and 

ridges of the Appalachian Mountains create a pattern of blue (valleys) and 

A broad swath of 

blue-green covers much of the arid lands of the West, from the sand hills of Nebraska to the deserts of Arizona, New Mexico, Nevada, and southeastern 

Here agricultural productivity 

is low, and economic motivation for building a dense road network is generally 

Across the Interior West, where 

higher road densities (blue or yellow) occur, there is an association with water availability for agriculture (along the Rio Grande in New Mexico, for example), natural resource extraction, or dense of severe accessibility issues. 
Image Properties This image depicts the average distance to nearest road (DTR) value in 1-km squares for the lower 48 (conterminous) United States. Averages were calculated from the 30-meter resolution NORM ED dataset.

Ave

in