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The Island Park Caldera just east of Yellowstone.

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The Centennials form both the Continental Divide and the Idaho/Montana border for 62 miles, from Monida Pass at I-15 to Red Rock Pass east of Yellowstone National Park. The range 12 miles in wide in places. In the west, the range begins as series of high rolling ridges that gradually gain in elevation as one moves to the east. On its eastern end, the range climbs abruptly out of the forested Island Park Caldera to form a high rugged crest that reaches its highest elevation at 10,203 feet on Mount Jefferson.