This dataset contains site information and results of flood-frequency analysis for 422 streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in parts of the Upper Mississippi and Souris-Red-Rainy basins and surrounding areas in the United States. Annual peak-flow data from the 1844 - 2013 water years were used in the study (U.S. Geological Survey, 2024). Following federal guidelines for flood-frequency analysis (Bulletin 17C; England and others, 2018) and methods outlined in recent flood-frequency reports for the region (Eash and others, 2013; Southard and Veilleux, 2014; Levin and Sanocki, 2023; Sanocki and Levin, 2023), the Expected Moments Algorithm (EMA) was used in version 7.5.1 of USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006; https://water.ugsgs.gov/software/PeakFQ/) to conduct the analyses. Results of the analyses, specifically the at-site skew and its mean squared error, are intended for use in Bayesian weighted least-squares/Bayesian generalized least-squares (B-WLS/B-GLS) regression (Veilleux and Wagner, 2019; Veilleux and Wagner, 2021) to model regional skew for the study area. Peak-flow (.pkf), specification (.psf), output (.PRT), and export (.EXP) files from PeakFQ and a .csv file containing site information and selected results of flood-frequency analyses are provided.