Spirit Mound Historic Prairie in South Dakota is a prominent hill on the Great Plains known both for Native traditions and for the Lewis and Clark Expedition’s visit on August 25, 1804. Plains tribes associated the mound with powerful and dangerous beings often described as little people, and later Lakota tradition also preserved its sacred and threatening character. The site is especially significant because it remains one of the few places along the altered Missouri River landscape that can be confidently identified as a spot where Lewis and Clark stood. After decades of private ownership and damage following white settlement, the area was protected, restored, and established as a state park, though debate continues over recreational use of a sacred place.