Currently in its third phase, the North American Forest Dynamics (NAFD) project is completing nationwide processing of historic Landsat data to provide a comprehensive annual, wall-to-wall analysis of U.S. disturbance history over the last 25 years. Because understanding the cause of disturbance is important to many forest-related applications, Forest Service scientists and collaborators have developed methods to map forest disturbance agents through time. Starting with 10 pilot scenes across the U.S. representing diverse disturbance regimes, scientists developed annual maps at 30 meters (98.42 feet) resolution of fire, harvest, conversion, stress and other agents. It was no surprise that high magnitude disturbances such as clear cuts, land use change, and severe fire could be mapped quite accurately, but the group also experienced success in mapping more subtle and slow disturbances such as insect and disease outbreaks in the Interior West. Research partners plan to distribute annual nationwide maps depicting when and where a forest disturbance occurred over the last 25 years in the near future. Forest Service scientists also are processing national causal agent maps and intermediate spatial data layers. These causal disturbance maps will enable extensive analyses of temporal and spatial patterns in disturbance agents across the U.S.