This is the Patronal Feast Day of the United States of America and a Holy Day of Obligation
The holy day Mass times are:
Vigil Mass, Thursday, December 7th, 7:00 PM, and
Friday, December 8th: 6:30 AM, 9:00 AM, 12:00 Noon, and 7:00 PM.
In anticipation that she was to bear the Son of God, Mary was preserved from the time of her conception from Original Sin. We call this the Immaculate Conception, and we recognize that Mary’s life began the moment she was conceived in the womb of St. Anne. No sin would touch her so that she would be a fitting and worthy vessel of the Son of God. The Immaculate Conception does not refer to the virginal conception and birth of Christ, but rather to Mary’s being conceived without inheriting Original Sin.
In the United States, a celebration of this observance predates the Declaration of Independence. The bishops commended the nation for the patronage of Mary under the title of the Immaculate Conception in 1846. It became a nationwide holy day in 1885.