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. Most GPR service providers have limited knowledge of soils and are unable to foretell the general suitability of the soils within project areas to GPR. Knowledge of the general suitability of soils would help service providers assess the appropriateness of using GPR and the likelihood of achieving acceptable results. Soil attribute data contained in the United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS) State Soil Geographic (STATSGO) and the Soil Survey Geographic (SSURGO) databases have been used to prepare GPR soil suitability maps of the United States and individual states at different scales and levels of resolution. Attribute data used to determine the suitability of soils include taxonomic criteria, mineralogy, clay content, electrical conductivity, sodium absorption ratio, and calcium carbonate and calcium sulfate contents. Ground-penetrating radar soil suitability maps show the relative suitability of GPR for soil investigations within different areas of the United States. These maps can help GPR service providers assess the effectiveness of GPR in project areas.