Montana Territory organized from Washington and Dakota territories

Background. Prior to 1864, the lands comprising Montana were distributed among several territories. Areas east of the Continental Divide belonged to Nebraska and Dakota territories, acquired via the Louisiana Purchase. The western portions originated from the Oregon Territory, which had been split off as part of Washington Territory. The boundary between Washington and Dakota was the Continental Divide.

Enabling Legislation. The creation of Montana Territory was formalized through the Organic Act of 1864. This legislation prescribed a standard organization for the territorial government, including the appointment of a governor, secretary, and supreme court members by the President with Senate consent. The government was designed as a training ground for statehood, allowing institutions to mature.

Political Context. The organization of Montana was influenced by political maneuvering, particularly by Sidney Edgerton, who became the first Territorial Governor. The change was partly due to Congress unifying the area with the creation of Idaho Territory in 1863. The boundary between Idaho and Montana followed the Bitterroot Range north of 46°30′ north.