Archbishop
Hughes became an archbishop on July 19, 1850, when the diocese was elevated to the status of archdiocese by Pope Pius IX. As archbishop, Hughes became the metropolitan for the Catholic bishops serving all the dioceses established in the entire Northeastern United States. He convened the first meeting of the Ecclesiastical Province of New York in September 1854. After this he traveled to Rome, where he was present at the proclamation of the Immaculate Conception as a dogma of the Catholic Church by Pope Pius. Hughes served as President Lincoln's semiofficial envoy to the Vatican and to France in later 1861 and early 1862. Lincoln also sought Hughes' advice on the appointment of hospital chaplains. On 3 September 1855, Archbishop Hughes traveled to St. John's, Newfoundland for the consecration of the new Roman Catholic Cathedral.
In an address in March 1852, Hughes lionized what he referred to as the "spirit of the constitution," expressed hope that the "parties" of the republic would be completely "penetrated" by that spirit, and stated that the founders' achievements in the realm of religious freedom were "original" in history and that the constitution's "negation of all power to legislate" on "rights of conscience" made American law on that topic superior to that of other countries which had secured these rights "by some positive statute." In the same address, Hughes also expressed sentiments of religious toleration, stating that "we are indebted" to the "liberality of Protestantism," in light of the fact that the framers of the Constitution "were almost, if not altogether, exclusively Protestants." He averred that the strong leadership of Washington and the variety of opposing Protestant views were likely more influential to the framers' stance on religious freedom than was Protestantism itself.
Hughes also stated that "the great men who framed the Constitution saw, with keen and delicate perception, that the right to tolerate implied the equal right to refuse toleration, and on behalf of the United States, as a civil government, they denied all right to legislate in the premises, one way or the other." He affirmed the role of Catholic soldiers in American wars and declared, "I think I shall be safe in saying that there has not been one important campaign or engagement in which Catholics have not bivouacked, fought, and fallen by the side of Protestants, in maintaining the rights and honor of their common country." Hughes also said that "It is... out of place, and altogether untrue, to assert or assume that this is a Protestant country or a Catholic country. It is neither. It is a land of religious freedom and equality; and I hope that, in this respect, it shall remain just what it now is to the latest posterity" and also that "Catholics, as such, are by no means strangers and foreigners in this land.... The Catholics have been here from the earliest dawn of the morning."