McAllister Glacier lies in North Cascades National Park in Washington, filling a large cirque north and east of Dorado Needle among steep alpine summits. Inspiration Glacier is nearby to the south and Klawatti Glacier to the east, separated by Tepeh Towers and by Klawatti Peak with a north-running arête. The glacier is about 1.85 miles long and roughly 1.5 miles wide at its terminus, descending from around 8,000 feet to about 4,500 feet near a proglacial lake. Like many glaciers in the North Cascades, it has been retreating, receding about 1,350 feet between 1975 and 2009 as part of the range’s broader glacier loss.