In 1827 a syndicate largely composed of army officers, stationed at Fort Snelling, made a claim of several hundred acres of land at and near the junction of the St. Croix and Mississippi rivers. A small trading post was soon erected and in 1849 a town was organized and named Elizabeth. The name was later changed to Prescott in honor of it's original founder. In 1853 Pierce County became a separate county with the county seat at Prescott and in 1857 the town of Oak Grove was taken off from the town of Prescott.

In 1861 the Rev. James Stehle came to Big River, then Oak Grove, for the first time and had Divine Services in a home on the Feast of All Saints. He was the priest of Hudson, St. Croix County at the time. The congregation at Big River consisted of eleven German families and five single men. A little log church was completed in 1862 and cemetery located one half mile north of the church. Then in 1872 a frame building was started and completed the following year at the present site.

The congregation grew and grew and in 1892 the Bohemians left the parish of St. Mary's and built a little church at Cherma (so called after their home in Bohemia), named St. Martins in the town of River Falls. St. Martins became a mission parish of St. Mary's and operated until it's official closing in October 1987.

St. Mary's was enlarged, remodeled and redecorated over the years and has only improved with age. She sits on top of a hill between Prescott and Ellsworth, WI overlooking fields, hills and valleys, and has been called the "Little Cathedral". Celebrating the 125^th anniversary of the church, in 1997 visitors were impressed with the beautiful high altar, stain glass windows and statues. With the many new homes being built in the area, St. Mary's will undoubtedly continue to grow. One thing will always remain the same though, the great faith of her people and their generosity and hard work keeping their parish in wonderful condition.