In 1959, Pope John XXIII redesignated the Diocese of Galveston as the Diocese of Galveston-Houston, and elevated Houston’s Sacred Heart parish to the unusual status of co-cathedral, shared with the St. Mary cathedral basilica in Galveston. As the population of Houston boomed, more than doubling in the second half of the 20th century, the diocese outgrew the space, and in 2002 Pope John Paul II approved the design of a new co-cathedral of the Sacred Heart.