Slate Peak is a 7,440-foot (2,270-metre) mountain summit located on the shared border between Okanogan County and Whatcom County in Washington state. It is part of the Okanogan Range, which is a sub-range of the North Cascades. The mountain is situated 15 miles (24 km) northwest of Mazama, on the boundary line of the Pasayten Wilderness, on land managed by the Okanogan–Wenatchee National Forest. The peak has the distinction of having the highest road in Washington, as well as the highest fire lookout. Although the narrow one-lane white-knuckle road reaches the summit of the mountain, the Forest Service gated it to vehicles, which necessitates walking the final few hundred yards. Additionally, the Pacific Crest Trail traverses the west slope of the peak, and the West Fork Pasayten Trail traverses the eastern slope. The nearest higher peak is Devils Peak, 2.57 miles (4.14 km) to the north. Precipitation runoff from Slate Peak drains east into Pasayten River, or west into Slate Creek, which is in the Skagit River drainage basin.