Jan 01, 1875St. Mary’s, Plattsburg St. Mary’s, Plattsburg Leave a Comment / By Staff / January 1, 1875 St. Mary’s, Plattsburg, January 1875. Date closed, currently unknown. Diocesan Timeline Related 'St. Mary’s, Plattsburg' Topics Timeline of The Diocese of West Missouri Tagged Founding of a church Click or tap on a topic or tag to see similar posts.