The Magsat-derived magnetic anomaly field over the United States was inverted to magnetization in a seismically determined variable-thicknees lower crust. The results are quite similar to those obtained from a previous inversion of POGO data. The average magnetization is 3.45¿1.0 A/m, which gives a bulk magnetic susceptibility of 8.7¿2.4¿10-2 (SI units) for the lower crustal layer consistent with a mafic composition. These values are also consistent with previous estimates of lower crustal magnetization from aeromagnetic data and with laboratory measurements of mafic rock susceptibilities.