Probability estimates for the occurrence of earthquake, hurricane, flood, and tornado disasters with 10 and 1000 fatalities per event in the United States during 1, 10, and 20 year exposure times, and estimates of the mean return time in years. Note the reversal in recurrence times for small and large events. Floods and tornadoes have relatively short return times for small events, while earthquakes and hurricanes have relatively short return times for large events.