Issued in 1954, this three-cent stamp marks the sesquicentennial of the Lewis and Clark Expedition of 1804-1806. The design features Meriwether Lewis, William Clark, and their Shoshone guide, Sacagawea, on the banks of the Missouri River. The expedition was a monumental undertaking, covering some 8,000 miles of western North America. The Corps of Discovery documented new species of plants and animals, mapped the vast territory, and established trade relations with numerous Native American tribes. This stamp celebrates the scientific, diplomatic, and exploratory successes of one of the most significant journeys in American history.