Monitoring drought is made difficult by the fact that droughts vary by intensity, duration, spatial extent, and the impacts they cause. In 1999, a joint effort was initiated to begin the weekly assessment of drought conditions across the United States using an ensemble of indicators. Four agencies and local officials around the country work to develop a map each week. This map is called the U.S. Drought Monitor. A new drought classification scheme was developed so that drought severity is depicted by four categories, along with a fifth category indicating the potential for developing drought conditions. A narrative describing conditions in greater detail accompanies the map, along with a web site providing the various indicators, tools, and additional information useful in creating the map. The Drought Monitor also attempts to distinguish impacts by identifying when agricultural, hydrological, or wildfire impacts are the dominant impact. Interest has been growing to adapt the drought monitoring concept of the Drought Monitor in other parts of the world.