The Roman Catholic Diocese of Biloxi encompasses 17 counties in south Mississippi. It was erected on March 1, 1977, when it was split from the Roman Catholic Diocese of Jackson. The diocese is part of the ecclesiastical province of Mobile, though for the first three years of its existence it was in the province of New Orleans. The Cathedral of the Nativity of the Blessed Virgin Mary, in Biloxi, Mississippi, is the diocese's cathedral.