These polygon features represent the maximum extent of the 37 named glaciers in Glacier National Park and two glaciers on U.S. Forest Service’s Flathead National Forest land during the peak of the Little Ice Age (mid-nineteenth century). Glacial margins are based on moraine deposits that result from active glaciation, and do not depict perennial snow and ice. Moraines were digitized based on WorldView imagery acquired on the following dates: 20141019, 20150822, 20150912, 20150925, 20160821, 20160915 (World View 01 and World View 03 satellites). High resolution imagery was supplemented with oblique aerial photographs flown in 2009 and 2016, historic photographs from the USGS photograph collection, and field notes from a 1914 USGS survey. Digitization was completed by Chelsea Martin-Mikle (USGS) and local knowledge and interpretation were provided by Dan Fagre and Lisa McKeon (USGS) in February, 2017 – February, 2018. Glacier margins were digitized at 1:2000 scale, with lowest off-nadir image chosen when multiple WorldView images were available for the same day. File attributes list specific photos used in analysis.