An understanding of the relationship between the physical characteristics of the landscape and fire occurrence is necessary to determine the potential risk of fire to human development adjacent to wilderness. Boundaries of severe fires were delineated on recent aerial photography (1994) and correlated with USFS fire records of the area. A GIS was used to determine which attributes of the physiography in the study area played leading roles in influencing the accuracy of aerial photo delineation of recent fires. This accuracy assessment was used to improve estimates of historical fire derived by delineating fires on older (1937) photos.