Data from 316 boreholes (including coreholes) that penetrated buried pre-Middle Jurassic basement rocks that lie beneath Atlantic and Gulf Coastal Plain sedimentary deposits in Florida and Alabama were compiled from non-proprietary, mostly published sources in order to support subsurface geologic mapping, geologic interpretation of geophysical data (aeromagnetic, gravity, seismic), topical studies as in geochronology, and applications ranging from mineral, energy, and water resources to earthquake hazards. Boreholes into bedrock beneath the coastal plain near the Fall Line in Alabama reveal buried extensions of geologic units exposed in the Piedmont, and those near the Gulf coast and beneath Florida provide rare insights into deeply buried rock units that have no surface exposures. Data for each borehole include the State, a unique identifier (well_ID), borehole name or location, year drilled, land surface elevation in feet, top-of-basement depth in feet, total depth of borehole in feet, top-of-basement elevation in feet, basement penetrated by drilling in feet, depth reference (ground level, Kelly bushing, or derrick floor), lithology code, basement type, quality of lithologic data, description of pre-Cretaceous basement rock, sample (drill core or cuttings), latitude and longitude (NAD27), county or city, and reference citations. The data in comma separated values (.csv) format are accompanied by an explanation (.txt), references (.txt), and metadata (.xml). The data file uses standard abbreviations for mineral names where necessary to save space.