A saint’s feast day can be the day of their actual death or a day assigned by the Church. Typically, the Church only assigns a day when the day of death is unknown or if several other saints are already assigned to that day. The number of canonized saints, however, is greater than the number of days in a calendar year. So two or more saints often share the same feast day. Because overlap often occurs, and the Church isn’t sure of the date of death of some saints, other calendar dates are sometimes chosen — such as the day that the saint was canonized.
Some saints’ feasts are only celebrated in the particular saint’s town or country. Others are internationally celebrated.For example, St. Patrick’s Day, March 17, is celebrated in Ireland, because St. Patrick is the patron saint of the entire nation. St. Patrick’s Day is also celebrated in many areas of the United States due to the Irish immigrants who crossed the Atlantic. Many U.S. dioceses have cathedrals dedicated to St. Patrick, or he’s the patron saint of the diocese. Celebrating the Feast of St. Patrick is a big occasion and a solemnity, a full-blown liturgical feast, in such places. In other places, such as Italy, Spain, France, Poland, and Germany, St. Patrick’s feast day isn’t celebrated with the same fanfare.
Another example is St. Joseph’s Day, March 19, which is celebrated in Canada and Europe with more hoopla than in the United States. He’s the patron of the universal Church and the head of the holy family, which refers to Jesus, Mary, and Joseph during the first 30 years of Jesus’ life. Mediterranean people remember him in particular with special foods and festivities, and his day is also a full solemnity all over the world. If his feast day falls on a Friday in Lent, then abstinence from meat and any fasting are dispensed to give the day full recognition. The reason is obvious due to the belief about Joseph’s role in the early life of Jesus: As the husband of Mary and foster father of Jesus, he took care of Mary and Jesus.
On some feast days, Catholics process through the streets and host festivals with plenty of pomp and circumstance. And with some feasts, parishes often have a special Mass and may even have a nine-day novena, which usually concludes on the day of the feast itself.
In addition, on the feast days of the founders of religious orders, the religious orders that they founded usually honor the feast of their founder with a healthy mix of praying and partying.
You can find saints for different places and saints for different occasions. The idea isn’t to replace or diminish the role of Christ as the one sole mediator but to show how the family of faith continues to remain a part of each member in different ways.