The spatially and topographically dependent nature of pumped storage hydropower (PSH) has placed it at a disadvantage when assessing deployment potential in comparison to other storage technologies such as batteries and thermal energy storage. While batteries can be assumed to be installed where needed, and thermal energy storage benefits from prior analysis and modeling for PV and CSP, long-term energy planning has often struggled to understand how much PSH resource is feasible and where it could be located. However, PSH is a mature and proven method of energy storage with competitive round-trip efficiency, long lifespans, and crucially the ability to store energy over long timeframes with little loss of stored energy. These qualities make PSH a very attractive potential solution to energy storage needs, as variable wind and solar production continue to comprise an ever-larger portion of the country’s energy mix. Realizing this potential has so far been challenging because a large-scale resource assessment of potential PSH in the United States has not existed—until now. We are proud to present the first comprehensive nationwide closed-loop PSH resource assessment for the United States as the result of a three-year effort undertaken at the National Renewable Energy Laboratory (NREL), as part of the U.S. Department of Energy (USDOE) HydroWIRES Initiative. This session will present and explore a new nationwide dataset of potential closed-loop PSH systems, the high-resolution geospatially explicit methodology used to create it, and a resource assessment of what the dataset implies for U.S. PSH deployment potential. Methodology developed at the Australian National University to detect potential closed-loop PSH using a source digital elevation model was adapted to the U.S. context and run for the entire country using a high-resolution 30-meter elevation input. A land use filter was applied to enforce technical and regulatory restrictions on development. This filter was informed by and is compliant with similar filters applied in NREL’s solar and wind resource potential analysis. The spatial locations and geometries of a large universe — tens of millions — of potential reservoirs were generated along with relevant attributes such as reservoir volume, dam volume and elevation. Reservoirs were paired into possible systems using spatial search to find other reservoirs within a suitable distance with the necessary elevation difference. A cost model was applied for each reservoir pair, and a least-cost algorithm was used to create a final dataset of the most cost-competitive potential PSH systems across the country. We show that the potential for a large amount of closed-loop PSH still exists in the United States, even after accounting for incompatible land uses and cost filters: tens of thousands of potential PSH systems with several terawatts of generation capacity and several tens of terawatt-hours of storage potential. However, we find PSH resource is concentrated in mountainous regions in the west and Appalachia, so despite substantial resource there are still challenges with distance to load and complementary generation technologies.