 The Nebraska State Legislature has credited Nebraska City as being the oldest incorporated city in the state, as it was the first approved by a special act of the Nebraska Territorial Legislature in 1855.Nebraska City is home of Arbor Day, the Missouri River Basin Lewis and Clark Center (which focuses on the natural history achievements of the expedition), and the Mayhew Cabin, the only site in the state recognized by the National Park Service as a station on the Underground Railroad.Early European-American official exploration was reported in 1804 by Lewis and Clark as they journeyed west along the Missouri River.