United Stated and Ireland.
The Eastern Church started a feast called the Conception of Mary in the seventh century. The Roman Catholic Church accepted this feast in the eighth century. This is the only one of Mary's feasts that did not originate in Rome, but was accepted by Rome.
There was a move in the eleventh century to describe Mary's conception as "immaculate". In 1854 Pope Pius IX defined the Immaculate Conception as Church dogma when he said "The most Blessed Virgin Mary, in the first instant of her conception, by a singular grace and privilege granted by almighty God, in view of the merits of Jesus Christ, the saviour of the human race, was preserved free from all stain of original sin.".