Expansion of the US wildland-urban interface
Document Type: Journal Article
Author(s): David M. Theobald; William H. Romme
Publication Year: 2007

Cataloging Information

  • catastrophic fires
  • coniferous forests
  • deciduous forests
  • fire danger rating
  • fire exclusion
  • fire intensity
  • fire management
  • fire regimes
  • forest management
  • forest types
  • GIS
  • grasslands
  • land management
  • land use
  • land use change
  • national forests
  • Pinus contorta
  • Pinus ponderosa
  • population density
  • shrublands
  • spatial analysis
  • vegetation surveys
  • wetlands
  • wildfire hazard
  • wildfires
Record Maintained By:
Record Last Modified: December 16, 2018
FRAMES Record Number: 46791
Tall Timbers Record Number: 22599
TTRS Location Status: In-file
TTRS Call Number: Fire File
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.


For at least two decades, expansion of low-density residential development at the wildland-urban interface has been widely recognized as a primary factor influencing the management of US national forests. We estimate the location, extent, and trends in expansion of the wildland-urban interface (WUI) in the continental United States. We mapped the WUI by determining the intersection of housing density classes computed from refined US Census data with a map of wildfire hazards based on broad forest types using definitions of WUI from the Federal Register. Our methods allowed us to provide a more spatially precise estimation of the WUI that better reflects development patterns of interest to forest land managers. We defined three wildfire hazard classes based on vegetation type. ''High'' severity applies to vegetation types in which stand-replacing fires dominate both historical and recent fire regimes, e.g., lodgepole pine forest. ''Low'' severity applies where fuels and climate foster mostly low-intensity fires, e.g., aspen-birch forest. ''High (historically low or variable)'' applies to vegetation types in which fires historically were of low or variable intensity, but recently have often burned at high intensity because of a century of fire exclusion, e.g., southwestern ponderosa pine forest. In 2000, the WUI that includes a 3.2 km community protection zone occupied 465,614 km2, and contained over 12.5 million housing units. This is an expansion of over 52% from 1970, and by 2030 the WUI is likely to expand to at least 513,670 km2 with the greatest expansion occurring in the intermountain west states. Roughly 89% of the WUI is privately owned land and about 65% of the WUI occurs in high or high (historically low or variable) severity fire regime classes. © 2007 Elsevier B.V. All rights reserved.

Theobald, D. A., and W. H. Romme. 2007. Expansion of the US wildland-urban interface. Landscape and Urban Planning, v. 83, no. 4, p. 340-354. 10.1016/j.landurbplan.2007.06.002.