Abstract
Rapid development of land in the wildland-urban interface (WUI) has had a significant impact on wildfire regimes by altering land cover and increasing the number of wildfire ignitions. In this study, we examine the effect of housing density on fire frequency across ten western U.S. states from 2000 to 2017. Our results indicate that human-caused wildfire ignitions do increase with housing density. The effect, however, is concave with significant impacts occurring for densities in the range of 0.05 to 0.80 houses/ac. We also find that all of the results are driven by places with below-average levels of average annual precipitation. Land-use projections using our model coefficients highlight the increased risk for ignitions in WUI areas bordering large metro areas across the West.