The Dubuque Diocese was created on July 28, 1837 by Pope Gregory XVI. Bishop Mathias Loras was named the first Bishop of the Dubuque Diocese. Loras gathered funds and personnel for the new Diocese, and he arrived in 1839. St. Raphael’s became the Cathedral parish in August of that year. He oversaw the expansion of the church in the early years of the diocese, first in the Iowa territory, then after 1846 in the new state of Iowa.

On June 15, 1893 the Dubuque Diocese was elevated to an Archdiocese by Pope Leo XIII. Bishop John Hennessey was elevated to become the first Archbishop of Dubuque at that time.  The Archdiocese of Dubuque is the only U.S. Archdiocese outside a major metropolitan area.

There are 199 parishes in the Archdiocese. There are three Catholic colleges in the Archdiocese: Clarke and Loras Colleges in Dubuque, and Mount Mercy University in Cedar Rapids. There are a number of religious orders with a presence in the Archdiocese. Notable orders include the Trappist monastery New Melleray Abbey(male) southwest of Dubuque, and the Trappistine monastery, Our Lady of the Mississippi Abbey (female) south of Dubuque.

The Archbishop of Dubuque is Michael Owen Jackels.