Louisiana Purchase State Park preserves two important Arkansas legacies: the initial point of the 1815 Louisiana Territory land survey and one of the state's few headwater swamps. An elevated boardwalk provides safe views of the swamp's plant and animal life and leads to the granite monument marking the survey's initial point. In 1921, while checking the Phillips and Lee County lines, surveyors found witness trees that had been marked during the 1815 survey. The L'Anguille Chapter of the National Society Daughters of the American Revolution in Marianna, Arkansas, recognized the discovery's historical importance and dedicated the commemorative monument on October 27, 1926. The site became Louisiana Purchase State Park in 1961. Early park development was supported by local citizen groups through the Green Thumb program. In 1977, the Arkansas Natural Heritage Commission added the swamp to the registry of Natural Areas and provided funds to purchase 37.5 acres. Arkansas State Parks has since developed the park, and together these efforts preserve it for future generations.