Pierce Mountain is a 4,973+ ft summit in the North Cascades Range of Washington, United States. It is located within North Cascades National Park and Stephen Mather Wilderness. It is situated above Ross Dam, at the eastern culmination of Sourdough Mountain. Like many North Cascade peaks, Pierce Mountain is more notable for its large, steep rise above local terrain than for its absolute elevation. Precipitation runoff from the mountain drains into the Skagit River via Pierce Creek and Ross Lake.