Big Horn County: Brief History
Big Horn County was originally formed 02 February 1865 as one of the original nine counties of Montana Territory. Back then it incompassed the majority of eastern Montana, from the Canadian border above, to Wyoming below, Chouteau and Gallatin counties on the west, and Dakota Territory along it's eastern edge.
Prior to 1869, white settlers in this area were few and far between. All government for Big Horn County was handled in Gallatin County.
The upper half of Big Horn County was organized to create Dawson County on 15 January 1869. A portion was designated as the Crow Indian Reservation in 1872. On 16 February 1877 the remainder of Big Horn County was renamed Custer County in rememberance of G. A. Custer and his men who had been annihilated here the previous year. At that point, Big Horn County suffered the same fate as Custer. Dust to Dust.
On 13 January 1913, thirty five years later, a new county was organized from parts of Rosebud and Yellowstone Counties and Big Horn County was revitalized. It is located in what was once its own vast backyard, although now just a fraction of what it used to be.
Along with the legendary Big Horn River and the Custer National Battlefield, Big Horn County is the home of approximately 12,850 people of which 60% are Native American. Its county seat is Hardin. It covers almost 5,000 square miles, with an average of 2.5 people per square mile. The Crow Indian Reservation covers 64.2 percent of its land area. The Northern Cheyenne Indian Reservation covers 6.37 percent. Another 20 square miles is water.
For the genealogy researcher, you won't find the usual census, birth, marriage, death records for Big Horn County from its demise in 1877 until its reincarnation in 1913. For those lost years, you must locate the area where your ancestors lived and look for the appropriate county. Keep in mind that the county names and boundaries have evolved over the years. (see Research / Montana Territory, State and County Formation)