Publications & Products

New analyses reveal WUI growth in the U.S.

Research Issue

Map - The 2010 Wildland-Urban Interface of the Conterminous United States Wildland-urban interface (WUI) areas – where houses and other development meet or mix with undeveloped natural areas – are places of transition and change. Undeveloped wildlands offer extensive opportunities for outdoor recreation and the aesthetic and personal advantages of living “in the country.” At the same time, human development changes wildlands over time, eating away at the edges or breaking large natural areas into smaller patches. Our recent study found that WUI grew rapidly from 1990 to 2010 in the U.S., expanding from 30.8 to 43.4 million homes (a 41% increase), covering from 581,000 to 770,000 km2 (33% growth), making it the fastest growing land use type in the conterminous U.S. New WUI area totaled 189,000 km2, an area that is larger than Washington State. This expansion of the WUI poses particular challenges for wildfire management, creating more buildings at risk to wildfire in environments where firefighting is often difficult.

Our Research

We have been studying the WUI in the U.S. for more than 10 years, looking at where WUI areas were once located, where they are now, and where we expect them to be in the coming decades. Our new data set provides the first high-resolution data on WUI change from 1990 to 2010, revealing how housing growth and wildland vegetation have combined over time. We developed new algorithms that converted the decennial Census standalone data into a consistent dataset on housing growth across the conterminous U.S. Downloadable GIS datasets and metadata are available for public use from the Forest Service Data Archive at http://dx.doi.org/10.2737/RDS-2015-0012-2. Mapping the WUI requires several processing steps. For more information, contact the authors.

Why This Matters

WUI areas may seem far from urban population centers but what happens in the WUI does not stay in the WUI. New development and roads can help introduce or spread invasive plants and animals to natural areas. Wildfires that begin in the WUI can grow to threaten structures at the edges of cities, destroy city dwellers’ vacation homes, or produce smoke that causes visibility and health problems for people living many miles away. The U.S. Forest Service and other agencies that manage our national forests, grasslands, and parks need to be aware of new development at the edges of those wildlands. The WUI atlas provides valuable information for policy makers, land managers, fire managers and others who want to learn about WUI locations at the local, state, or national scale.

Research Results

Radeloff, Volker C.; Helmers, David P.; Kramer, H. Anu; Mockrin, Miranda H.; Alexandre, Patricia M.; Bar-Massada, Avi; Butsic, Van; Hawbaker, Todd J.; Martinuzzi, Sebastián; Syphard, Alexandra D.; Stewart, Susan I. 2018. Rapid growth of the US wildland-urban interface raises wildfire risk. Proceedings of the National Academy of Sciences. 24: 201718850-. https://doi.org/10.1073/pnas.1718850115.

Radeloff, Volker C.; Helmers, David P.; Kramer, H. Anu; Mockrin, Miranda H.; Alexandre, Patricia M.; Bar Massada, Avi; Butsic, Van; Hawbaker, Todd J.; Martinuzzi, Sebastián; Syphard, Alexandra D.; Stewart, Susan I. 2017. The 1990-2010 wildland-urban interface of the conterminous United States - geospatial data. 2nd Edition. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2015-0012-2.

Martinuzzi, Sebastián; Stewart, Susan I.; Helmers, David P.; Mockrin, Miranda H.; Hammer, Roger B.; Radeloff, Volker C. 2015. The 2010 wildland-urban interface of the conterminous United States. Research Map NRS-8. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 124 p.

Research Partners

  • Miranda H. Mockrin, U.S. Forest Service Northern Research Station
  • Volker C. Radeloff, Department of Forest Ecology and Management, University of Wisconsin-Madison
  • David P. Helmers, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison
  • Susan I. Stewart, U.S. Forest Service Northern Research Station, People and Their Environments – Research Social Scientist (retired)
  • Sebastián Martinuzzi, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison
  • Roger B. Hammer, School of Public Policy, Oregon State University

For additional information, please contact Miranda Mockrin.



Last Modified: July 16, 2018