Magnetic data collected as part of a high-resolution airborne magnetic and radiometric survey over parts of Maryland, Pennsylvania, and West Virginia are provided here as a flight line database, grids, and imagery. The dataset was acquired as part of the USGS Earth Mapping Resource Initiative (Earth MRI) to improve our understanding of the fundamental geologic framework of the region with applications to evaluating natural resources and geologic hazards. Magnetic surveys measure subtle variations in the Earth's magnetic field and can detect differences in the magnetic properties of rocks from ground level to many kilometers below. The data were acquired and processed by Sander Geophysics Ltd. (SGL) under contract to Dewberry and the USGS. Data collection took place August 2022 to April 2023 using a combination of fixed-wing airplanes and helicopters. Pre-planned flight lines were flown in an E-W direction with 250-m line spacing; N-S tie-lines were flown with 2500-m line spacing. The nominal flight height of 120 meters (m) above ground, with areas having higher population densities flown at a nominal height of 330 m above ground for safety reasons. A total of 212,312 linear kilometers of data were collected covering an area that is 350-km E-W and 200 km N-S at its widest dimensions. A circular region surrounding the Catoctin Mountain Park was not covered. Details regarding the flights and data processing are described in the contractor report provided on the landing page of this release.