Fort Owen State Park, Historic trading post and settlement site in Stevensville, United States.

Fort Owen State Park is a one-acre historic site on the northern edge of Stevensville, Montana. Its only original structure is the East Barracks, whose back wall, parts of the side walls and interior walls are adobe brick made and erected by Father Pierre-Jean De Smet and his associates in 1841 and 1842. Visitors can also see fort foundations uncovered by University of Montana excavations from 1957 to 1980, plus reconstructions of an 1850s cabin, a root cellar and a well house.

St. Mary's Mission was founded on this site in 1841 by Father Pierre-Jean De Smet, the first permanent white settlement and first Catholic church in Montana. In 1850 John Owen, a former sutler at Fort Hall, bought the mission for $250, the first recorded land transaction in Montana, and renamed it Fort Owen. He and his Shoshone wife Nancy ran it as a trading post; in 1860 he replaced the wooden stockade with adobe brick walls.

John Owen and his Shoshone wife Nancy ran the post together, serving fur trappers, traders, missionaries and explorers. Owen, who had been a civilian sutler at Fort Hall, bought the mission site for $250 in 1850, the first recorded land transaction in Montana. The fort was also, for a time, the chief Indian agency for the area.

Fort Owen State Park is a one-acre plot surrounded by private property, open every day of the year. Volunteers from the Stevensville Historical Society occasionally staff the site, but visitors mostly rely on interpretive signs to learn about the mission and the fort. The park lies on Stevensville Cutoff Road, south of Missoula, just off U.S. Route 93 on the northern edge of Stevensville.

The East Barracks is the only original structure left; its back wall and parts of the side and interior walls are adobe brick made by Father De Smet and his companions in 1841 and 1842. Excavations by the University of Montana between 1957 and 1980 exposed the fort's foundations, which visitors can still see.