With approximately 312 glaciers, North Cascades National Park has the most glaciers of any US park outside Alaska, and a third of all the glaciers in the lower 48 states. Counting a few glaciers in the adjoining National Recreation Areas, the North Cascades National Park Complex glaciers covered an expanse totaling as of 2009. Boston Glacier, on the north slope of Boston Peak, is the largest glacier in the park, measured in 1971 to have an area of . Other glaciers that were measured in 1971 to be larger than 2 square kilometers include East Nooksack and Sulphide Glaciers on Mount Shuksan, McAllister and Inspiration Glaciers on Eldorado Peak, Redoubt Glacier on Mount Redoubt, Neve Glacier on Snowfield Peak, and Challenger Glacier on Mount Challenger.