During the spring and summer of 2020, the U.S. Geological Survey, Lower Mississippi – Gulf Water Science Center, conducted single well slug tests on selected wells within the Mississippi Alluvial Plain of Arkansas and Mississippi to estimate hydraulic conductivity (K) and transmissivity (T) values for the aquifers in which the wells are screened. A total of 324 test were conducted on 48 wells. The computer software AQTESOLV for Windows (Duffield, 2007) was used to interpretate the slug test data to estimate K and T values. Mean estimates of K for the 44 wells completed in the Mississippi River Valley alluvial aquifer ranged from 3 to 401 feet per day (ft/day) and mean estimates of T ranged from 285 to 80,559 square feet per day (ft2/day). Mean estimates of K for the 4 wells completed in the Sparta Sand or 500-foot Sand (Memphis Aquifer) that make up part of the middle Claiborne aquifer of the Mississippi embayment aquifer system ranged from 0.14 to 183 ft/day and mean estimates of T ranged from 55 to 67,913 ft2/day. This Data Release contains the following data and supporting metadata: 1. A PDF document with calibration information for the mechanical slugs used for testing. 2. A zipped file of the 48-site files folders containing: 1. The site’s slug test field form (pdf). 2. Digital images of the site (jpg). 3. Water-level pressure transducer log files (csv), 4. Excel files(s) of transducer data with Time vs. Water Depth plots and the selected Time – Displacement data used for analysis. 5. The AQTESOLV solution report files (aqt) for each slug test. 3. A summary data file in two formats (csv & GIS shape file) including the following information for each site: 1. Site information [site name, agency code, USGS National Water Information System (NWIS) site number] 2. Location information (latitude, longitude, state, county). 3. Well construction information [well depth and diameter, casing diameter, top and bottom of opening (screen), and opening (screen) length]. 4. Aquifer information (local and national aquifer codes, and aquifer thickness). 5. Slug test information (test date and static water-level). 6. Estimates information (minimum, mean, median, and maximum K and T values and the solution method). 4. An equipment documentation file (csv) listing the water-level tape, transducer, and slug used at each site. 5. A water-level documentation file (csv) listing the before and after testing water-level measurements for each site. 6. A model input file (csv) listing the values input into the model for each test. 7. A model solutions file (csv) listing both the “Visual” and “Auto” match solution estimates for the slug tests at each site. Additional information, including discussions of the hydrogeologic setting, well descriptions, slug testing and analysis methods, and a summary of the slug test results are available in the Open File Report associated with this Data Release (Pugh, 2021). This dataset was collected and analyzed as part of the U.S. Geological Survey, Mississippi Alluvial Plain Regional Water-Availability Study.