Agassiz Glacier lies in Glacier National Park, Montana, in a cirque southeast of Kintla Peak on the west side of the Continental Divide. Named for Swiss-American glaciologist Louis Agassiz, it is one of several park glaciers monitored by the U.S. Geological Survey to measure changing glacier mass. Researchers use remote sensing, repeat photography from the same viewpoints, and tree-ring studies to track its retreat and reconstruct its earlier extent. Their findings show substantial shrinkage: between 1966 and 2005, the glacier lost about one-third of its surface area, making it an important example of environmental change in the park.