This data release provides digital flight line data for a high-resolution airborne magnetic survey over parts of Montana in the vicinity of the Boulder Batholith. The airborne survey was jointly funded by the Earth Mapping Resources Initiative and Kennecott Exploration Company. The survey was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 34,041 line km of magnetic and radiometric data were acquired over an irregular-shaped area of 6178 km2. Data were collected from a helicopter flown at a nominal terrain clearance of 100 meters (m) above topography along E-W flight lines spaced at 200 m intervals. Tie lines were flown in an N-S direction every 2000 m. Data were collected by Sander Geophysics Limited (SGL), and Dewberry Engineers, Inc. under contract with the USGS using a helicopter with a magnetometer mounted in a stinger. The survey operated out of the Butte, Montana, airport from June of 2022 to August of 2022. Files that are available in this child item include flight line data for the magnetic survey, grids, and a geotiff of the gridded total-field anomalies.