There are national days for lots of things. Some serious, some frivolous; some sad, some fun.
But I've searched a bit, and I cannot find any proclamation or declaration for
National Community Theatre Day
There should be one. By far, the largest community of actors and theatre workers in the world comprises local amateur and semi-professional theatre people.
I know there is a "World Theatre Day", but no National or International Community Theatre Day.
There should be one.