The wildland–urban interface (WUI) is the area where houses meet or intermingle with undeveloped wildland vegetation. The WUI is thus a focal area for human– environment conflicts, such as the destruction of homes by wildfires, habitat fragmentation, introduction of exotic species, and biodiversity decline. Our goal was to conduct a spatially detailed assessment of the WUI across the United States to provide a framework for scientific inquiries into housing growth effects on the environment and to inform both national policymakers and local land managers about the WUI and associated issues. The WUI in the conterminous United States covers 719 156 km²(9% of land area) and contains 44.8 million housing units (39% of all houses). WUI areas are particularly widespread in the eastern United States, reaching a maximum of 72% of land area in Connecticut. California has the highest number of WUI housing units (5.1 million). The extent of the WUI highlights the need for ecological principles in land‐use planning as well as sprawl‐limiting policies to adequately address both wildfire threats and conservation problems.

Following a survey of forest homeowners in rural Michigan to assess the value of reducing the risk of damage from wildfires at the wildland-urban interface, focus group discussions were conducted with a subset of survey participants to learn about their perceptions concerning specific components of fire hazard (e.g., how fires start, fire control, fire damage), their understanding of how fire protection responsibility is allocated between government and individuals, and their under standing of and preferences for alternative fire management strategies. Focus-group data were analyzed using a framework based on behavioral economics and psychometric models of risk. Attributes associated with the fire risk help explain the relative popularity of different fire protection strategies. Because participants consider forest fires inherently uncontrollable, and the resulting damage essentially random, they are only weakly supportive of investments in firefighting infrastructure, unlikely to take all possible steps to safeguard their own properties, and resolute in their emphasis on solutions that reduce the number of fire ignitions. Their universally negative perceptions of prescribed fire may ultimately preclude its use as a risk management tool in Michigan's wildland-urban interface forests.

In the present study, we examine housing growth in California, Oregon, and Washington in the wildland–urban interface (WUI), the area where homes and other structures abut or intermingle with wildland vegetation. We combine housing density information from the 1990 and 2000 USA censuses with land cover information from the 1992/93 National Land Cover Dataset to demarcate the location and extent of the WUI and its growth, both in terms of area and number of housing units during the 1990s. We overlay the WUI with coarse-scale fire regime condition class information to evaluate implications for wildland fire management. During the 1990s, WUI area in the three-state region increased by 5218 km2 (10.9%) to nearly 53 000 km2 and the number of housing units in the WUI increased over 1 million units (17.6%) and in 2000 encompassed 6.9 million units, 43% of all housing in the region. Over a million new homes were constructed in the WUI, comprising 61% of the new homes constructed in the region. By 2000, there was far more intermix WUI (75% of the WUI area and 64% of the WUI housing units) than interface WUI. Expansion of the WUI accounted for only 13% of WUI housing unit growth and WUI that existed in 1990 encompassed 98% of WUI housing units in 2000. In 2000, there were nearly 1.5 million WUI housing units in areas with 0–35-year fire return intervals and 3.4 million in areas with 35–100+ year fire return intervals. In both these fire regimes, the majority of WUI housing units (66% and 90% respectively) are in areas with a current condition outside the historic range of variability. Housing growth patterns in this three-state region are exacerbating wildland fire problems in the WUI. Any long-term solution to wildland fire issues in the western United States will have to address housing growth patterns. Using a consistent, nationally applicable assessment protocol, the present study reveals the vast extent of WUI in the west coast states and its growth in the 1990s, and provides a foundation for consistent monitoring efforts.

Land managers need consistent information about the geographic distribution of wildland fuels and forest structure over large areas to evaluate fire risk and plan fuel treatments. We compared spatial predictions for 12 fuel and forest structure variables across three regions in the western United States using gradient nearest neighbor (GNN) imputation, linear models (LMs), classification and regression trees (CART), and geostatistical methods (kriging and universal kriging (UK)). Local-scale map accuracy varied considerably across sites, variables, and methods. GNN performed best for forest structure variables in Oregon, but LMs and UK were better for canopy variables and for forest structure variables in Washington and California. Kriging performed poorly throughout, and kriging did not improve prediction accuracy when added to LMs as UK. GNN outperformed CART in predicting vegetation classes and fuel models, complex variables defined by multiple attributes. Regional distributions of vegetation classes and fuel models were accurately represented by GNN and very poorly by CART and LMs. Despite their often limited accuracy at the local scale, GNN maps are useful when information on a wide range of forest attributes is needed for analysis and forest management at intermediate, i.e., landscape to ecoregional, scales.