We compared the potential fire behavior and smoke production of historical and current periods based on vegetative conditions in 49 5,100- to 13,500-ha watersheds in six river basins of eastern Oregon and Washington. Vegetation compositions, structure, and patterns were attributed and mapped from aerial photographs of 1932 to 1959 (historical) and 1981 to 1992 (current). Vegetation with homogeneous composition and structure were delineated as patches.