Hydrologic landscape regions (HLRs) in the United States were delineated by using geographic information system (GIS) tools and statistical methods including principal components and cluster analyses. The GIS and statistical analyses were applied to land-surface form, geologic texture (permeability of the soil and bedrock), and climate variables that describe the physical and climatic setting of 43,931 small (roughly 200 square kilometers) watersheds in the United States. The analyses then grouped the watersheds into 20 noncontiguous regions (the HLRs) on the basis of similarities in land-surface form, geologic texture, and climate characteristics.

This hydrologic landscape regions dataset contains for each of the 43,931 watersheds the (1) watershed identification number, (2) land-surface form, geologic texture, and climate characteristics for each watershed, and (3) hydrologic landscape region number for each watershed.