The 1864 Organic Act created Montana Territory and provided a basic government structure for the new territory, including a territorial governor, secretary and three judges appointed by the president of the United States, and a territorial legislature and non-voting representative to the U.S. House of Representatives elected by eligible voters in the territory. The act called for the legislature to meet annually for 40 days, except for the first legislature, which was granted a 60 day session. The territorial governor was to decide the date and places of the first election, apportion the members of the two houses and choose the date and place for the first legislature to meet. Thereafter, the legislature itself was to decide dates for future elections and legislative sessions and apportion seats.

After conducting a census of the territory, which he used to apportion the 7 seats of the Territorial Council and 13 seats of the House of Representatives, Territorial Governor Sidney Edgerton held the first territorial election on October 24, 1864. The first territorial legislature met from December 12, 1864 through February 9, 1865. They passed nearly 100 bills, but did not apportion seats in the legislature for future elections. The legislature contained an even distribution of Republicans and Democrats. Edgerton, a Republican, insisted that members of legislature swear to the "Iron Clad Oath," which included a statement that they had never borne arms against the U.S. Government. J. H. Rogers could not swear to the oath and was forced to resign his seat, creating immediate tension between Edgerton and the members of the legislature.

Sources: Margery H. Brown, "Metamorphosis and Revision: A Sketch of Constitution Writing in Montana," Montana: The Magazine of Western History Vol. 20 No. 4 (Fall 1970), pp 2-17; James McClellan Hamilton, History of Montana: from Wilderness to Statehood, (Portland, Oregon, Binfords and Mort : c1970); Michael P. Malone, Richard B. Roeder and William L. Lang, Montana: A History of Two Centuries, Revised Ed. (Seattle: Univeristy of Washington Press, 1991); Robert G. Athearn, "The Civil War and Montana Gold: The Great War Muddies the Mountain Waters," Montana: The Magazine of Western History Vol. 12 No. 2 (Spring 1962), pp. 62-73.