Mastodon State Historic Site in Imperial, Missouri preserves the Kimmswick Bone Bed, one of the nation’s most extensive Pleistocene ice age sites, where mastodon and other extinct animal remains were first found in the early 19th century. Its national importance rests on both paleontology and archaeology. In 1979, scientists uncovered a Clovis culture stone spear point directly associated with mastodon bones, providing the first solid evidence in American archaeology that people and mastodons coexisted. Saved from destruction during Interstate 55 construction by state purchase in 1976, the site was added to the National Register of Historic Places in 1987 and now offers museum exhibits and public access.