Territorial evolution of Montana

The following chronology traces the territorial evolution of the U.S. State of Montana.

An enlargeable map of the United States after the Constitution of the United States was ratified on March 4, 1789.
An enlargeable map of the United States after the secret Third Treaty of San Ildefonso transferred the Spanish colony of la Luisiana to the French Republic on October 1, 1800.
An enlargeable map of the United States after the Louisiana Purchase took effect on December 20, 1803.
An enlargeable map of the United States after the creation of the District of Louisiana on March 26, 1804.
An enlargeable map of the United States after the creation of the Territory of Louisiana on March 3, 1805.
An enlargeable map of the United States after the creation of the Territory of Missouri on June 4, 1812.
An enlargeable map of the United States after the Treaty of 1818 took effect on January 30, 1819.
An enlargeable map of the United States after Missouri was admitted to the Union on August 10, 1821.
An enlargeable map of the United States after the Oregon Treaty took effect July 17, 1846
An enlargeable map of the United States after the creation of the Territory of Oregon on August 14, 1848.
An enlargeable map of the United States after the creation of the Territory of Washington on March 2, 1853.
An enlargeable map of the United States after the creation of the Territory of Kansas and the Territory of Nebraska on May 30, 1854.
An enlargeable map of the United States after the admission of Oregon to the Union on February 14, 1859.
An enlargeable map of the United States after the creation of the Territory of Dakota on March 2, 1861.
An enlargeable map of the United States after the creation of the Territory of Idaho on March 3, 1863.
An enlargeable map of the United States after the creation of the Territory of Montana on May 26, 1864.
An enlargeable map of the United States after the admission of Montana to the Union on November 8, 1889.
An enlargeable map of the United States as it has been since Hawaiʻi was admitted to the Union on August 21, 1959.