This dataset is a point shapefile of wells measured for the potentiometric surface maps of the Mississippi River Valley alluvial aquifer (MRVA) in Spring 2016, 2018, and 2020. The data provided for each well considered in the applicable potentiometric surface map are the water-level date, altitude [relative to the North American vertical datum of 1988 (NAVD88)], a useYYYY code (which is positive if the water level was used in the potentiometric surface map for that year), a use comment (which is populated for water levels not used), and the water-level change values, for 2016-18, 2018-20, and 2016-20 for water levels with positive useYYYY codes for the applicable years. The data provided for each streamgage considered in the applicable potentiometric surface map are the measurement date, surface-water altitude (relative to NAVD88), a useYYYY code (which is positive if the surface-water level was used in the potentiometric surface map for that year), a use comment (which is populated for surface-water levels not used), and the surface-water-level change values for 2016-18, 2018-20, and 2016-20 for surface-water levels with positive useYYYY codes for the applicable years. The location and static information for each well and streamgage, for example: latitude and longitude, were derived from the latest available data in the data files used in the potentiometric surface maps. Since the publication of the potentiometric surface maps for Spring 2016, 2018, and 2020, there have been updates to the well's location information (latitude, longitude, and station name) and, for a small subset of wells, it was determined that the identification code (SiteBadge) should be modified to eliminate duplicate wells. The new location information and SiteBadge are appended to well data, if appropriate.