When Raymond Cardinal Burke was appointed Prefect of the Supreme Tribunal of the Apostolic Signatura by His Holiness Pope Benedict XVI, on June 27, 2008, he was serving as the Archbishop of St. Louis. Since all prelates of the Church are linked to a diocese, the Holy Father determined that Cardinal Burke would continue his relationship with the Archdiocese of St. Louis and gave him the status of Archbishop Emeritus.
Although Cardinal Burke lives in Rome, where he currently serves as the Cardinal Patron of the Sovereign Order of Malta, he continues to have an official Church affiliation with the Archdiocese of St. Louis.
Note: Bishops of the Church are given to the faithful by Christ to act as their shepherds. They are in charge of a "Diocese" which is usually a geographical area made of local parishes.
Not all bishops occupy pastoral positions as the heads of dioceses. Bishops are always chosen and appointed by the Pope. In some of the Eastern rites of the Church bishops are appointed at a synod of bishops and the choice is then ratified by the Pope giving him the final decision over the appointment.
Since all bishops must have a diocese under their care, bishops who are not in charge of a "real" diocese of their own, are given "Titular Episcopal Sees." A Titular Episcopal See is a diocese of which the bishop is the titular head. By naming Cardinal Burke "Emeritus" of the Archdiocese of St. Louis, he retains his diocesan affiliation.