Missouri is a state in the Midwestern region of the United States. It has eight neighboring states and is the 18th most populous state with about 6.16 million residents. The name Missouri comes from a Native American word that means "river of the big canoes". The state has various nicknames, such as the Show Me State, the Mother of the West, and the Cave State. Missouri has a diverse geography, with plains, forests, mountains, and rivers. The Missouri River is the longest river in North America and runs through the state from west to east. The state's capital is Jefferson City and its largest city is Kansas City. Missouri has a rich history and culture, being the site of many important events and movements in American history, such as the Missouri Compromise, the Pony Express, the Dred Scott case, and the Gateway Arch.