This dataset contains modeled hourly streamflow in cubic meters per second at each of about eighteen thousand selected operational and water-quality stream gage locations. It was assembled from publicly available retrospective V2.1 National Water Model outputs (See NWM Retrospective source info). The streamflow variable was extracted from model output files and the data were reshaped to optimize read performance. The stream gage locations were derived from several ongoing USGS project gages for evaluation of streamflow, water quality, and real-time monitoring, however only National Water Model identifiers and NHDPlusV2.1 catchment outlet locations (as contained in the National Water Model output files) are used to identify model results. Relationships between U.S. Geological Survey National Water Information Service gages and National Water Model prediction locations were not reviewed for release at the time of publication of this data. Please contact the author for up-to-date information. All processing resources used for data reformatting and extraction can be found in this repository: https://code.usgs.gov/water/nwm_subset. This supporting code also contains Docker images that are capable of processing real-time National Water Model outputs into similar formats as this dataset and provide data services via the THREDDS Data Server. The retrospective is available in one NetCDF file. These data conform to the NetCDF-CF Discrete Sampling Geometry conventions. The retrospective data are available from public cloud data outlets (such as: https://noaa-nwm-retrospective-2-1-pds.s3.amazonaws.com/index.html). More information on these data is available from the Office of Water Prediction National Water Model page here: https://water.noaa.gov/about/nwm. Additional release notes are available here: https://www.weather.gov/media/notification/pdf2/scn20-119nwm_v2_1aad.pdf. This pdf has been archived with this data release.