Research Cave, near Portland, Missouri, is a major Native American archaeological site in a sandstone outcrop above the Missouri River. Its low passages and interior chambers preserved evidence of human habitation reaching back about 8,000 years, with materials spanning roughly seven to ten thousand years. The cave is especially significant for exceptionally early clothing and footwear, including leather-wrapped moccasins dated to about 5,500 years ago, among the oldest known human clothing finds in North America. Later, settler John Phillips mined saltpetre there for gunpowder. Despite its importance, mixing of deposits, damage at the cave mouth, and looting have harmed the archaeological record.