Fichier:St Peters Mission Montana - pre 1908.jpg

Identifiable structures include the two-story wood frame boys' school (left), the Ursuline stone convent and school (center left), the opera house (center right), and original wood frame girls' school (center right low, with tower).

Catholic Jesuit priests established St. Peter Mission in 1860 on the Sun River about 8 miles (13 km) upriver from Fort Shaw, Montana. They moved the mission 2 miles (3.2 km) downstream in 1862, but this location proved difficult for agriculture. In April 1866 the mission moved again, this time to a position 2 miles (3.2 km) south Bird Tail Rock (which is 15 miles (24 km) south of the town of Simms, Montana). The mission closed almost immediately due to hostility from a nearby Native American tribe, the Piegan Blackfeet, but reopened in 1874. The mission moved again in 1881 to Birch Creek (a point 10.5 miles (16.9 km) west-northwest of Cascade, Montana). The 1881 location is depicted here. At some point between 1874 and 1881, the Jesuits built a wood frame structure to house a school for boys.

In January 1884, the new (and founding) Bishop of the Roman Catholic Diocese of Helena, Jean-Baptiste Brondel, invited the Ursuline religious order of women to join the Jesuits at St. Peter's Mission and assist them in educating the Native Americans. Five Ursuline sisters arrived in October 1884. In 1885, they built several log cabins and a wood frame structure that contained a chapel and classrooms for girls. This structure also had a two-and-a-half story bell tower. The Ursulines built a three-story stone building with basement beginning in 1892, into which the girls' school moved in 1896. This structure was funded by donations from the future Saint, Katharine Drexel, a Philadelphia, Pennsylvania, heiress. This building also served as the nuns' convent. Over time, the Jesuits and Ursulines built a bakery, barn, corral, laundry, and workers' housing. The Ursulines—who believed in music and art training as well as education in reading, math, and science—also built an opera house at St. Peter's in 1896. The Jesuits stopped educating boys, turning that function over to the nuns.

The boys' school closed in 1896, and fire destroyed it in 1908. The Ursulines moved their school into nearby Great Falls, Montana, in 1912. Fire destroyed the stone convent/school and the girls' wood frame school in 1918. St. Peter's was largely abandoned afterward.