Did you know that the study of flags is called vexillology? That information, and much more, here.
And if you still need to know more about Flag Day, try this.
The common thread in the Flag Day articles I looked at is that it is somehow a "forgotten holiday." That's interesting, since according to our President, respecting our flag is one of the things that binds Americans together. Maybe people just respect it all the time and don't need a special day to do so.
We already had our Flag Day, here. It's a different day. But then, it's a different flag!
7 hours ago