Madison Junction is the hinge of the Lower Loop, the place where the West Entrance Road ends at a T and meets the Grand Loop. The Firehole and Gibbon rivers join here to form the Madison, and the skyline carries part of the Yellowstone Caldera rim along with the lava flows that buried much of it. National Park Mountain stands among those flows. Drivers on this tour pass through twice: first heading south for the geyser basins, and again at the very end, arriving from Norris after 94 miles of loop. Early expeditions reached this junction on trails Native people had already made. West Yellowstone lies 14 miles back along the entrance road, so the junction also marks the decision point for anyone leaving the park at the end of the day.
Two rivers stop here and a third one starts. At the junction ahead, the Firehole and the Gibbon meet and make the Madison. Now look past the water at the high dark wall. Part of what you're seeing is the rim of the Yellowstone Caldera, thirty by forty-five miles across, left by the third and most recent big eruption, six hundred thirty-one thousand years ago. The rest is lava. National Park Mountain is actually part of those flows. Don't go hunting for a steaming crater. The caldera is hard to see because it's so big, and lava has mostly filled the hole. You'll see this junction twice. The first time it sends you south to the geysers. The last time you'll come down from the north, and that's where the loop closes.
Photo: NPS Photo / Jim Peaco · Public domain