Kansas ( KAN-zəss) is a state in the Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named after the Kansas River, in turn named after the Kansa people. Its capital is Topeka, and its most populous city is Wichita; however, the largest urban area is the bi-state Kansas City, MO–KS metropolitan area. For thousands of years, what is now Kansas was home to numerous and diverse Indigenous tribes. The first settlement of non-indigenous people in Kansas occurred in 1827 at Fort Leavenworth. The pace of settlement accelerated in the 1850s, in the midst of political wars over the slavery debate. When it was officially opened to settlement by the U.S. government in 1854 with the Kansas–Nebraska Act, conflict between abolitionist Free-Staters from New England and pro-slavery settlers from neighboring Missouri broke out over the question of whether Kansas would become a free state or a slave state, in a period known as Bleeding Kansas. On January 29, 1861, Kansas entered the Union as a free state, hence the unofficial nickname "The Free State". Passage of the Homestead Acts in 1862 brought a further influx of settlers, and the booming cattle trade of the 1870s attracted some of the Wild West's most iconic figures to western Kansas. As of 2015, Kansas was among the most productive agricultural states, producing high yields of wheat, corn, sorghum, and soybeans. In addition to its traditional strength in agriculture, Kansas possesses an extensive aerospace industry. Kansas, which has an area of 82,278 square miles (213,100 square kilometers) is the 15th-largest state by area, the 36th most-populous of the 50 states, with a population of 2,940,865 according to the 2020 census, and the 10th least densely populated. Residents of Kansas are called Kansans. Mount Sunflower is Kansas's highest point at 4,039 feet (1,231 meters).