It is a holiday in much of the English speaking world on the first Monday in August; it is a day off in the Caribbean to the south of America and Canada to the north. It is not in honour of anything in particular; it is just that somebody decided that we all deserved a three day weekend at the height of summer. But not in America; it's nose to the grindstone as usual.
Walter Kim, writing in the New York Times, called America "a nation of remarkably productive, often well-paid workers who are becoming increasingly reluctant to pause from their labors and refresh their souls -- a nation whose cash-drenched corporate employers typically don't pay for much time off (less than two weeks annually, on average), a nation whose globe-gripping federal government is the only one in the whole industrialized world not to legally require generous periods of paid kick-back-and-hang time -- is a nation that's socially screwed up, particularly in comparison with European countries like France, which orders its citizens outside to play for the entire month of August and a few other weeks spread through the year."
Some say that the drop in attendance at National Parks is due to the lack of vacation time; others note that a lot of air travel is done because people are taking more quickie short vacations and have to get there fast. Certainly one long vacation is going to be more fuel efficient than a lot of short ones.