Understanding where landslide processes in California have been most severe is helpful in determining priorities for landslide mapping, mitigation measures, and preparedness planning. Although a few studies of landslide damage and fatalities have been published (see sources of data 12, 17, 34, 36, 40), and many more reports mention landslide damage and fatalities incidentally, our map is the first to show where the problem is most severe for the entire state.