News Release

Forest Service and University of Wisconsin Develop New Tools Identifying Wildland Urban Interface: Where Forests, Homes and Wildfires Meet

July 1, 2004 -

The U.S. Department of Agriculture Forest Service and the University of Wisconsin (Madison) today released new scientific maps depicting the communities and lands within the wildland urban interface (WUI) across the lower 48 states. This is the first consistent nationwide representation of the WUI as defined in the Federal Register (Volume 66:751, 2001) and makes possible mapping and analysis at national, state and local levels.

In all, 42 million homes or 37 percent of the nation’s total are in the WUI. These lands comprise 273,000 square miles or nine percent of the 48 states. The WUI, where houses meet or intermingle with wildland vegetation, is not only a high-value environment for users, but also a focal area for human-environment conflicts, such as wildland fires, habitat fragmentation, invasive species and biodiversity decline.

While this research delineates the WUI, it does not depict wildland fuel conditions or wildland fire risk or define communities at risk. The risk of fire varies widely across WUI areas.

“These findings clearly depict the potentially extensive scope of wildland fire issues confronting communities across the nation,” said Dr. Ann Bartuska, Forest Service deputy chief of research and development. “This information will help land managers focus on these critical areas and develop preventative measures as we continue to implement the Healthy Forests Initiative.”

Using geographic information systems, Forest Service and university researchers integrated U.S. Census Bureau housing data and U.S. Geological Survey National Land Cover data, to map the WUI based on housing data. While California leads the nation with more than five million homes within the WUI, North Carolina has the greatest area at more than 12 million acres. In 20 states, 50 percent or more of all homes are in the WUI.

“Our analysis, which integrates demographic and satellite information, is quite unique,” said Dr. Roger Hammer, assistant professor and researcher at the University of Wisconsin’s Applied Population Laboratory, Madison. “Our research provides the most current data on shifting population patterns and gives us the ability to analyze the growth and size of the WUI.”

The findings include analysis of how WUI areas burned during previous fire seasons. For example, while the devastating 2003 California wildfires affected 533 square kilometers (132,000 acres) of WUI areas and burned more than 3,600 structures, it represented only about five percent of southern California’s total interface area. Analysis of the Cedar Fire in San Diego County showed nearly the entire periphery of the fire was along the WUI.

This collaborative research was accomplished using National Fire Plan dollars.

The media should use the white-background (600 dots per inch) national, regional and state maps for graphical display. Images should be downloaded for best results.