A question from a friend:

There are 10 holy days of obligation, but only 6 are celebrated in the United States:

1. Solemnity of Mary (January 1)
2. The Ascension of Jesus (40 days after Easter)
3. The Asumption of Mary (August 15)
4. All Saints Day (November 1)
5. The Solemnity of the Immaculate Conception (December
6. Christmas (December 25)

The 4 holy days of obligation not celebrated in the United States are:

1. The Epiphany of Jesus (January 6)
2. Solemnity of St. Joseph, Husband of the Virgin Mary (March 19)
3. Corpus Christi
4. Solemnity of Saints Peter and Paul (June 29)

I would like to know why US Catholics have fewer holy days of obligation than the rest of the Catholic world.