Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This data release includes minimally processed (raw) AEM data as well as unprocessed and processed (diurnally corrected and draped to terrain) magnetic data, and unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data, all as supplied by Xcalibur Multiphysics https://www.sciencebase.gov/catalog/item/624bd4a6d34e21f82763663c. Data acquisition and minimal processing were conducted by Xcalibur Multiphysics and described in detail in the contractor's reports. Digital data from production flights are provided, and data fields are defined in the data dictionaries.