Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired November 2018 to February 2019 along 16,816 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. Resolve frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 30 m above terrain with 6- to 12-kilometer spaced east-west flight lines. The main survey block covers 13,641 line-km, including two north-south tie lines extending the length of the survey. Several rivers were surveyed along their center axes, covering 2,640 line-km (flight line numbers 8010000-8100001 nonsuccessive), and two separate inset grids were flown: (1) Crowley's Ridge in Arkansas with 1.5-km spaced east-west flights for a total of 406 line-km (flight line numbers 24025-24477 nonsuccessive) and (2) University of Memphis focus area in Tennessee with variable line spacing for a total of 129 line-km (flight line numbers 30010-30060 and 39010-39050 nonsuccessive). This data release includes the averaged and culled AEM data along all flight lines that were used to produce the final resistivity models (https://www.sciencebase.gov/catalog/item/5d76ba5ce4b0c4f70d01ff94). Digital data of the processed soundings are provided and fields are defined in the data dictionary (https://www.sciencebase.gov/catalog/item/5d76bac9e4b0c4f70d01ff9d).