Louis William Valentine DuBourg (; 10 January 1766 – 12 December 1833) was a French Catholic prelate and Sulpician missionary to the United States. He built up the church in the vast new Louisiana Territory as the Bishop of Louisiana and the Two Floridas and later became the Bishop of Montauban and finally the Archbishop of Besançon in France. Born in the colony of Saint-Domingue, DuBourg was sent to France at a young age to be educated and entered the Society of Saint Sulpice. As a cleric and son of a noble family, the French Revolution forced him into exile in Spain. In 1794, DuBourg sailed to the United States and began teaching and ministering in Baltimore, and became the president of Georgetown College in 1795. He significantly improved the quality of the institution, but mounted a substantial debt and was ousted by the Jesuit owners of the college in 1798. DuBourg then founded a lay collegiate counterpart to St. Mary's Seminary in Baltimore. He also selected the site of Baltimore's first cathedral and became the ecclesiastical superior to Elizabeth Ann Seton's newly founded Sisters of Charity. In 1812, DuBourg was made the apostolic administrator of the Diocese of Louisiana and the Two Floridas, and three years later, its bishop. Catholic New Orleanians rejected his authority and he was forced to move his episcopal seat to St. Louis, Missouri. There, he built the first cathedral west of the Mississippi River and established missions to the American Indians, dozens of churches, and numerous schools, including St. Mary's of the Barrens Seminary and Saint Louis University. He also recruited the Sisters of Loretto and Rose Philippine Duchesne's Sisters of the Sacred Heart to found several academies. Never able to establish his seat in New Orleans, DuBourg returned to France in 1826, where he was made the Bishop of Montauban. Just months before his death in 1833, he became the Archbishop of Besançon. Early life and education Louis-Guillaume-Valentin DuBourg was born in the city of Cap-Français (known today as Cap-Haïtien) in the French Caribbean colony of Saint-Domingue, likely on 10 January 1766. Born to a noble family originally from Bordeaux, France, his mother was Marguerite DuBourg née Armand de Vogluzan and his father was Pierre DuBourg, who held the titles of and . Pierre was a licensed sea captain and highly successful merchant in the coffee trade. Following the death of his mother,