More than 320 millions of years (MYA) ago, the area where Choteau now lies was covered by a inland sea. That sea is what led to the depositing of the great beds of limestone found in our mountains.
Then, 140 MYA to 50 MYA , the Sevier Orogeny (period of mountain uplift) created portions of the Rocky Mountain Front.
Later, some 70 to 83 MYA, the Two Medicine Formation was deposited between the western shoreline of the Late Cretaceous Interior Seaway and the eastward advancing margin of the Cordilleran (Mountain) Overthrust Belt. The Two Medicine Formation is mostly sandstone, deposited by rivers and deltas.
The Two Medicine Formation is famous for the “good mother lizard,” Maiasaura peeblesorum, but records a much more extensive fauna in sediments deposited for 14 million years, from about 83 million years ago to 70 million years ago.
About 50+ MYA, the Lewis Overthrust caused blocks of mostly sedimentary rock to be pushed as much as 60 miles eastward as a result of the Farallon Plate subducting off the West Coast.
More recently, about 110 to 191 thousand years ago- the Bull Lake period glaciers approached Choteau from the North and East. They left glacial deposits over the Choteau area.
About 12-15,000 years ago, the eastern edge of the Cordilleran ice sheet abutted the Laurentide ice sheet near Choteau. The Cordilleran sheet was anchored in the Coast Mountains of British Columbia and Alberta, south into the Cascade Range of Washington.
It is believed that the Cordilleran ice melted rapidly, in less than 4000 years.
The maximum advance of the Laurentide (Continental) Ice Sheet reached the bench above Choteau. At maximum extent, it blocked the drainages of north- and east-flowing rivers such as the Missouri River, forming glacial lakes along the margin of the ice.
One of these glaciers, the Shelby lobe, blocked the Milk River, creating Glacial Lake Twin River. Tributaries of the Marias River were also blocked by the Shelby lobe, leading to the formation of Glacial Lakes Cutbank and Choteau.
Lake Chouteau was a glacial lake formed during the late Pleistocene along the Teton River. After the Laurentide Ice Sheet retreated, water melting off the glacier accumulated between the Rocky Mountains and the ice sheet. The lake drained along the front of the ice sheet, eastward towards the Judith River and the Missouri River. Choteau was then under some 90 feet of water.
About 13,000 years ago, an ice free corridor between the Laurentide and Cordilleran Ice sheets allowed the first Native Americans to travel south into the Choteau area and points southward, a trail that became the Old North Trail.
The Old North trail was marked by prominent land forms- often uniquely shaped Mountains or Buttes.
In 1801, a Blackfoot headman named Old Swan drew a map for a Hudson’s Bay Company (HBC) officer named Peter Fidler. Fidler sent a copy of the map back to England, where a cartographer named Aaron Arrowsmith used it to define the center of his new map of North America. Old Swan’s map became an important reference map of the Old North Trail.
Old Swan’s map shows the following waypoints:
- Devils Head near Calgary, AB
- Chief Mountain near Babb, Mt
- Haystack Butte near Augusta, Mt
- Grizzly Peak, north of Helena
- Birdtail Butte, East of Sims, MT
- Belt Butte near Belt, Mt
- Wolf Butte near Geyser, Mt
- Coffin Butte near Harlowton, Mt
- Canyon Mountain south of Livingston, Mt
- An unidentified landmark in the Pryor Mountains
Since approximately 500 BC , the Blackfeet have followed the “Old North Trail” over the “Backbone of the World,” using dogs and dog travois to carry their household goods.
It was not until a time after about 1730, when Blackfeet were attacked by Shoshone on horseback, that Blackfeet saw horses which they call “Elk Dogs.” The Blackfeet soon adopted horses in place of the dog travois to travel the ONT.
In 1803, the United States acquired most of Montana through the Louisiana Purchase. The tribes of the Louisiana Purchase Territory officially came under U.S. jurisdiction.
1851- The Fort Laramie Treaty allocated much of northern Montana to the Blackfeet (Including the Choteau area) even though the Blackfeet did not take part in the treaty negotiations.
1855- The first Treaty between the Blackfeet and the United States sets the southern boundary of Blackfeet lands as the Sun River.
1859- A Jesuit mission is established at what is now Priest Butte, three miles south of Choteau. The mission closes the following spring.
1864- Montana Territory is formed. Choteau becomes part of Chouteau County.
1867 – The Blackfeet Indian Agency was moved to a location now known as The Old Agency, about 4 miles north of Choteau. Blackfeet chiefs had selected the location. The agency was built in a square stockade of cottonwood trees, 180 feet on a side, included a general store, school, cabins for workers, corrals and barns, a blacksmith shop and other buildings. The contract called for the complex to be called Fort Sherman, but that name was never used.
The Agency site has never been plowed and its archaeological remnants remain undisturbed. Depressions in the ground mark where buildings were, and the graves of 40 souls are still visible. The burial ground includes the grave of Mountain Chief, a historic Blackfeet leader.
The Northwest Fur Company and I. G. Baker and Brother operated licensed Indian trading posts near the agency where they pursued the lucrative business of bartering tobacco, beads and other essential goods for furs.
Fort Shaw is built on the Sun River, about 35 miles southeast of Choteau.
1872 – First school for Blackfeet children opened at Four Person Agency.
1873 – President Grant issued Executive Orders diminishing reservation lands. The 1873 Executive Order diminished 1851 and 1855 treaty lands and established an undivided reservation for the Blackfeet, Gros Ventre, Assiniboine, and Sioux. This territory spanned land north of the Missouri and Sun River east to the Dakota border.
1874 – By act of Congress, the Blackfeet reservation boundary moved northward from the Sun River to the Birch Creek – Marias River line. The Blackfeet are neither consulted nor remunerated. Old Agency was abondoned.
1870’s- The Metis move to the Front. The Teton Canyon Metis were descendants of the Pembina Band of Metis that fled Canada after the failed rebellion Led by Louis Riel of the Winnipeg area in the 1870’s. The Metis build a settlement in the South Teton Canyon near what is now the Pine Bluff Nature Conservancy Ranch. The settlement is occupied for more than 50 years.
1893- Teton County was formed out of Chouteau County. Choteau becomes the County Seat.
1913- The first Great Northern Railroad train arrives in early October followed soon by a new Milwaukee Railroad route.
1913- Choteau incorporates as a City.