The Province grew rapidly, experiencing a large increase in the number of its members and an ever-deepening presence across its vast geographical territory. In 1950, the provincial minister sent questionnaires to all the friars regarding the possibility of dividing the large geographic jurisdiction of the St. Joseph Province. The great majority favored the division. On February 2, 1952, this desire was realized, and the Province of St. Joseph and the Province of St. Mary were established as separate jurisdictions.

While the Province of St. Joseph stretched from Detroit to Montana, the newly formed Province of St. Mary included New York and New England and the mission territories of the Mariana Islands and Ryukyu Islands. Friars were given the choice as to which province they would join, and there was an almost even split between the two. Quickly, each province grew in number to nearly the size of the original single province.