This paper describes a current national analysis of streamflow data being conducted by the U.S. Geological Survey to identify and map, in a consistent State-by-State format, the frequency and areal distribution of major floods and droughts in the United States. The work is being performed as the latest in a series of National Water Summaries published as Geological Survey Water-Supply Papers. The flood-and-drought analysis is part of a nationwide Geological Survey program to assess the Nation's water resources.