Missouri is a U.S. state located in the Midwestern United States. Missouri's geography is highly varied. The northern part of the state lies in dissected till plains while the southern part lies in the Ozark Mountains (a dissected plateau), with the Missouri River dividing the two. The state lies at the intersection of the three greatest rivers of North America, with the confluence of the Mississippi and Missouri Rivers near St. Louis, and the confluence of the Ohio River with the Mississippi north of the Bootheel. The starting points of the Pony Express and Oregon Trail were both in Missouri. The mean center of United States population as of the 2010 Census is at the town of Plato in Texas County.
Missouri borders eight different states, as does its neighbor, Tennessee. No state in the U.S. touches more than eight states. Missouri is bounded on the north by Iowa; on the east, across the Mississippi River, by Illinois, Kentucky, and Tennessee; on the south by Arkansas; and on the west by Oklahoma, Kansas, and Nebraska (the last across the Missouri River). The two largest Missouri rivers are the Mississippi, which defines the eastern boundary of the state, and the Missouri River, which flows from west to east through the state, essentially connecting the two largest metros, Kansas City and St. Louis.
Although today the state is usually considered part of the Midwest, historically Missouri was considered by many to be a Southern state, chiefly because of the settlement of migrants from the South and its status as a slave state before the Civil War. The counties that made up "Little Dixie" were those along the Missouri River in the center of the state, settled by Southern migrants who held the greatest concentration of slaves.
In 2005, Missouri received 16,695,000 visitors to its national parks and other recreational areas totaling 202,000 acres (820 km2), giving it $7.41 million in annual revenues, 26.6% of its operating expenditures.
North of, and in some cases just south of, the Missouri River lie the Northern Plains that stretch into Iowa, Nebraska, and Kansas. Here, gentle rolling hills remain from the
glaciation that once extended from the Canadian Shield to the Missouri River. Missouri has many large river bluffs along the Mississippi, Missouri, and Meramec rivers. Southern Missouri rises to the
Ozark Mountains, a dissected plateau surrounding the Precambrian
igneous St. Francois Mountains. This region also hosts
karst topography characterized by high limestone content with the formation of sinkholes and caves.
The southeastern part of the state is the Bootheel region, part of the Mississippi Alluvial Plain or Mississippi embayment. This region is the lowest, flattest, and wettest part of the state. It is also among the poorest, as the economy is mostly agricultural. It is also the most fertile, with cotton and rice crops predominant. The Bootheel was the epicenter of the four New Madrid Earthquakes of 1811–1812.