Mary, under her title of the Immaculate Conception, has been patroness of the United States since the mid-19th century. But her protection of the nation dates back to its earliest history. 

One of the first Catholic churches in what is now the United States was dedicated to the Immaculate Conception in 1584: the now-Basilica of the Immaculate Conception, in Jacksonville, Fla. 

John Carroll, the first bishop in the United States, had a great devotion to the Blessed Virgin Mary. In 1792, he placed the diocese of Baltimore— which encompassed the thirteen colonies of the young republic— under her protection.

Over the next fifty years, seven more dioceses were created, including New Orleans, Boston, Chicago and Oregon City.

“The colonies were now the USA, and Baltimore was not the only diocese – so, the American hierarchy felt a need for a national protectress for this new republic,” said Dr. Geraldine M. Rohling, archivist-curator emerita for the Basilica of the National Shrine of the Immaculate Conception in Washington D.C.

U.S. bishops unanimously named Mary, under her title of the Immaculate Conception, patroness of the nation in 1846, during the Sixth Provincial Council of Baltimore. 

“We take this occasion, brethren, to communicate to you the determination, unanimously adopted by us, to place ourselves, and all entrusted to our charge throughout the United States, under the special patronage of the holy Mother of God, whose immaculate conception is venerated by the piety of the faithful throughout the Catholic church.... To her, then, we commend you, in the confidence that ... she will obtain for us grace and salvation,” the bishops wrote in a letter at the time.

Bl. Pius IX approved the declaration in 1847.

The Immaculate Conception refers to Mary being conceived without original sin. Today, it is a dogma of the Catholic Church. But back in 1846, it was not. B. Pius IX would promulgate the dogma of the Immaculate Conception in 1854, and many believe the U.S. bishops’ declaration may have influenced the pope’s decision. 

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The largest Marian shrine in the United States is dedicated to the Immaculate Conception— the Basilica of the National Shrine of the Immaculate Conception in Washington D.C. The first public Mass for the National Shrine was celebrated on the Feast of the Immaculate Conception in 1917, though the shrine was not yet constructed. 

The Immaculate Conception is also patroness of several other countries, including Spain, South Korea, Brazil, and the Philippines. 

The feast of the Immaculate Conception is celebrated Dec. 8, nine months before the Feast of the Nativity of Mary. It is a Holy Day of Obligation in some places, including the United States, Ireland, and the Philippines.