We propose to use the US high-voltage power transmission system as an extremely large antenna to extract unprecedented spatiotemporal space physical and geological information from distributed geomagnetically induced current (GIC) observations. The power grid impacts are presently the highest space weather concern in US and Federal Energy Regulatory Commission's ongoing regulatory action will drive substantial industry and federal interests in the GIC problem in the near future. Consequently, the proposed game changing GIC observations set up offers not only opportunity for new big heliophysics science utilizing industrial structures but also potential for major interagency and public-private collaborations. Geomagnetic storms drive geomagnetically induced currents (GIC) in high-voltage power transmission systems worldwide. GIC distribution in the transmission system is a function of the large-scale surface geoelectric field and DC characteristics of the transmission system. Geoelectric field carries information about magnetospheric-ionospheric electric current systems and geological structures. It is common to use information about magnetospheric-ionospheric electric current systems or geomagnetic field variations on the ground together with geological and transmission system description to model GIC. However, no work or technology exists for inverting spatiotemporal space physical and geological information from extensive distributed GIC observations. We will utilize the US high-voltage power transmission system for the first time as a science tool to map large scale GIC's. Large-scale application of the set up will allow unprecedented, game changing, extraction of space physical and geological information over wide range of spatial and temporal scales. Further, the new GIC observation set up can be turned into a valuable resource for the power transmission industry. We envision that the large-scale implementation of the concept can be carried out in collaboration with the industry and other federal agencies after the 1-year pilot phase. With sufficient funds, full-scale implementation of the concept with a larger number of GIC observation sites can be achieved within 2-3 years after the pilot phase.