USGS scientists are currently measuring differences in the force of gravity throughout the mountains of California and Alaska to provide basic research data, aid in the exploration of natural resources, and to locate hidden faults beneath populated areas. Previous gravimetric data helped to outline and define the extent of sedimentary basins with oil‐bearing deposits such as Cook Inlet near Anchorage. Measurements taken at a maximum spacing of five miles throughout California and fifteen miles throughout Alaska should be completed by 197