Nebraska is a triply landlocked state in the Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwest; and Wyoming to the west. Nebraska is the 16th largest state by land area, with just over 77,220 square miles (200,000 km²). With a population of over 1.9 million, it is the 37th most populous state and the 7th least densely populated. Its capital is Lincoln, and its most populous city is Omaha, which is on the Missouri River. Nebraska was admitted into the United States in 1867, two years after the end of the American Civil War. The Nebraska Legislature is unlike any other American legislature in that it is unicameral, and its members are elected without any official reference to political party affiliation.