The performance of ground-penetrating radar (GPR) is dependent upon the electrical conductivity of soils. Soils having high electrical conductivity rapidly attenuate radar energy, restrict penetration depths, and severely limit the effectiveness of GPR. Factors influencing the electrical conductivity of soils include the amount and type of salts in solution and the clay content. Data on the clay and soluble salt contents of soils were used to develop thematic maps showing at different scales the relative suitability of soils for GPR applications. The United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS) bases these maps on field experience and soil attribute data contained in the State Soil Geographic (STATSGO) and the Soil Survey Geographic (SSURGO) databases. Attribute data used to determine the suitability of soils include clay content, electrical conductivity, sodium absorption ratio, and calcium carbonate content. Each soil attribute was rated and assigned a value ranging from 1 to 10. These attribute values were summed and the most limiting (maximum) layer indices within depths of 1.0 or [Formula: see text] were selected to represent soil components. The dominant component value was selected as the GPR suitability index for each map unit. The GPR indices are displayed in graduated color maps. The STATSGO database was used to produce the Ground-Penetrating Radar Soil Suitability Map of the Conterminous United States. This map can be used to assess the relative appropriateness of GPR for soil investigations within comparatively large areas of the conterminous United States. The SSURGO database, which contains the most detailed level of soil mapping and information provided by the USDA-NRCS, can be used to produce larger scale maps showing more varied and intricate soil patterns that influence the effectiveness of GPR within selected soil survey areas.