STEVENSVILLE — St. Mary Parish has a long history in the Bitterroot. St. Mary Parish Catholic Church is right next to the historic St. Mary’s Mission, the first church built in what is now Montana. Check out the renovations here:Inside the renovations at Stevensville’s St. Mary Parish“This is a humble little parish. Father Severson said. “When people come and visit, they didn't always know this was the parish church.