On November 2, 1889, North Dakota and South Dakota were admitted to the Union as the 39th and 40th states. The first European explorers, Louis Joseph and François de La Vérendrye, entered the region in 1742 and 1743. At that time, at least eight Native American tribes populated the vicinity including the Mandan, Arikara, Kidatsa, Assiniboin, Crow, Cheyenne, Cree, and the Dakota (Santee Sioux).
Other than through fur trapping, exploration of the Dakotas by European-Americans was practically nonexistent prior to the 1803 Louisiana Purchase. In 1804, the Lewis and Clark Expedition wintered in present day North Dakota.
An increasing population caused Dakota Territory to be divided in half and a bill for statehood for both Dakotas titled the Enabling Act of 1889 was passed on February 22, 1889 during the Administration of Grover Cleveland. His successor, Benjamin Harrison, signed proclamations formally admitting both states on November 2, 1889. Harrison had the papers shuffled to obscure from him which he was signing first and the actual order went unrecorded.
On December 29, 1890, the Wounded Knee Massacre occurred on the Pine Ridge Indian Reservation. Commonly cited as the last major armed conflict between the United States and the Sioux Nation, the massacre resulted in the deaths of an estimated 300 Sioux, many of them women and children. Twenty-five U.S. soldiers were also killed in the conflict. The Wounded Knee area was later the site of a prolonged siege between members of the American Indian Movement and the United States Marshals Service in 1973.
Much of present-day North Dakota was included in the Louisiana Purchase of 1803. Much of acquired land was organized into Minnesota and Nebraska Territories. Dakota Territory, making up present-day North and South Dakota, along with parts of present-day Wyoming and Montana, was organized on March 2, 1861. Dakota Territory was settled sparsely until the late 1800s, when the railroads entered the region and aggressively marketed the land. A bill for statehood for North Dakota, South Dakota, Montana, and Washington titled the Enabling Act of 1889 was passed on February 22, 1889 during the administration of Grover Cleveland. After Cleveland left office, it was left to his successor, Benjamin Harrison, to sign proclamations formally admitting North and South Dakota to the Union on November 2, 1889. The rivalry between the two new states presented a dilemma of which was to be admitted first. Harrison directed Secretary of State James G. Blaine to shuffle the papers and obscure from him which he was signing first and the actual order went unrecorded. However, since North Dakota alphabetically appears before South Dakota, its proclamation was published first in the Statutes At Large. Since that day, it has become common to list the Dakotas alphabetically and thus North Dakota is usually listed as the 39th state. It is believed that nobody recorded which paper was signed first, thus nobody can actually know which of the Dakotas was admitted first.