Most studies of wildland fire and residential development have focused on the cost of firefighting and solutions such as fuel reduction and fire-safe home building. Although some studies quantify the number of homes being built near forests, little research has indicated the potential magnitude of the problem in the future. This article presents data illustrating this emerging problem for western communities. Our analysis takes a long view, looking at the potential for more home construction next to public forests and implications for future wildfire fighting costs. In a study of 11 western states, we found that only 14% of the available 'wildland interface' in the West is currently developed, leaving great potential for new home construction in the remaining 86%. If just one-half of the wildland interface is developed in the future, annual firefighting costs could escalate to $4.3 billion. By comparison, the Forest Service's annual budget is about $4.5 billion.