Geological Survey of Canada (GSC) has been acquiring aeromagnetic data since 1947. Over the years, more than 1000 surveys have been carried out, generally with a flight-line spacing of 800 m and an altitude of 305 m above the ground. These aeromagnetic surveys have been levelled to each other to correct for arbitrary datums, slow variations of Earth's magnetic field over time, and differing survey specifications. Since 2000, the majority of aeromagnetic surveys have been flown with a line spacing of 400 m or less. These data are archived in the Canadian Aeromagnetic Data Base.