The High Plains aquifer extends from about 32 degrees to almost 44 degrees north latitude and from about 96 degrees 30 minutes to 106 degrees west longitude. The aquifer underlies about 175,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set is comprised of water-level measurements from 7,698 wells measured in both 2015 and 2017, which were used to map water-level changes, 2015 to 2017. The map was reviewed for consistency with the relevant data at a scale of 1:1,000,000.