Description: The Lewis and Clark National Historic Trail is approximately 3,700 miles long, extending from Wood River, Illinois, to the Pacific Ocean in Oregon, following both the outbound and inbound routes of the Lewis and Clark Expedition. The trail connects 11 states (Illinois, Missouri, Kansas,Nebraska, Iowa, South Dakota, North Dakota, Montana, Idaho, Washington, and Oregon) and was established by Congress in 1978 as part of the national trails system (NTS) as one of four original national historic trails. This trail commemorates the 1804-1806 expedition of Lewis and Clark and the Corps of Discovery, which explored the Louisiana Territory and beyond. This epic journey contributed to significant scientific knowledge and profound political, social, economic, cultural, and environmental changes to the lands and the peoples of the North American continent. This data set represents the official National Park Service centerline of the historic route of the Lewis and Clark National Historic Trail. As of 2017, this feature class represents the National Park Service's best approximation of the historic route of the Lewis and Clark Expedition of 1804-1806. The spatial data is derived from ArcInfo coverage of the historic channel of the Missouri River developed by James D. Harlan of the University of Missouri; Lewis and Clark overland trail data created by Steve F. Russell of Iowa State University; and Lewis and Clark Trail Maps produced by Martin Plamondon II. Data in this format can be used on digital online maps or downloaded and used within desktop applications. Please see the access and user constraints below for more information.