How are Holiday Dates Determined?

MuffinBoy #2 here with a quick mini-muffin!

When we celebrated Father's Day recently, I got to wondering, "How are the dates of holidays decided?"  I already knew that some holidays are religious and based on ancient calendars, but what about more modern-day holidays like Father's Day or Mother's Day?

I went to the library and picked up a short book called, Holiday!  Celebrations Around the World.  It was a DK (Dorling-Kindersley) book, which are always awesome and full of great pictures.  This one was an easy reader, so there wasn't a whole lot of information, but it did answer my question.

I discovered that Father's Day originated when Louise Dodd's mother died, leaving her dad to raise a family of six children on his own.  She started the holiday in his honor.

About 100 years ago on the second Sunday in May, Anne Jarvis asked her friends to think of her dead mother and wear white carnations to church, which was the first celebration of Mother's Day.

Reading about these holidays and learning about their beginnings answered my question, but left me wondering how these holidays spread in popularity.  I suspect that the original families told other people, who told other people, etc. until Mother's Day and Father's Day became the widely celebrated holidays they are today.

Do you have any special family traditions you think should become national holidays??  Tell us about it!