Airborne electromagnetic (AEM) and magnetic survey data were collected from December 2022 through March 2023 over a distance of 11,079 line kilometers in western Nevada and eastern California; central Nevada; and northern Nevada and southeastern Oregon. These data were collected in support of the U.S. Geological Survey (USGS) Earth Mapping Resources Initiative (Earth MRI), which aims to improve knowledge of the geologic framework of the United States through new geological and geophysical mapping and to identify areas that may have the potential to contain critical mineral resources. Data were acquired by XCalibur Multiphysics with the HELITEM² time-domain helicopter-borne electromagnetic system together with the CS-3 Scintrex Cesium Vapour magnetometer. The survey was acquired at a nominal flight height of 35 meters (m) above terrain and an average height of 80 - 85 meters. AEM data were processed and inverted to produce models of electrical resistivity along flight paths, with typical total depth of investigation around 400 meters. The survey was divided into three areas of interest (AOI) and used four different configurations of the HELITEM² system: - AOI1 is located in western Nevada and Eastern California and covers numerous basins surrounding Clayton Valley and Rhyolite Ridge. The following system configurations were used: -- 21 meter diameter loop with 30 Hz base frequency. Data collected with this system are noted with the tag _21m_30Hz in the netCDF. -- 35 meter diameter loop with 7.5 Hz base frequency (system 1). Data collected with this system are noted with the tag _35m_7p5Hz_sys1 in the netCDF. -- 35 meter diameter loop with 7.5 Hz base frequency (system 2). Data collected with this system are noted with the tag _35m_7p5Hz_sys2 in the netCDF. - AOI2 is located in northern Nevada and southeastern Oregon and covers the region surrounding McDermitt Caldera. One system configuration with a 21 meter diameter loop and base frequency of 15 Hz was used for data collection. - AOI3 is located in central Nevada and covers Railroad Valley and surrounding basins. One system configuration with a 21 meter diameter loop and base frequency of 15 Hz was used for data collection. This is the same configuration used in AOI2.