The High Plains aquifer extends from south of 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 the water-level measurements from 7,526 wells measured in both 2013 and 2015, which was used to map water-level changes, 2013 to 2015. The map was reviewed for consistency with the relevant data at a scale of 1:1,000,000.