They say New York is the city that never sleeps.  There's always somewhere to go and something to do no matter what time of day (or night) it is.  I believe this to be because new york has so many people living in it, and so many people on different work/sleep/life cycles that business and such can justify staying open so late.  Here in pittsburgh, dowtown shops and restaurants are closed by 6pm.  When i was in vegas, that city never sleeps either.  you can go anywhere anytime of night and gamble and drink.  There are a lot of people there too.   So, as a city become more and more populated, it starts adjusting it's own day life to fit the needs of it's inhabitants.  Now, think of it on a national scale instead of just with a city.  You have places like wendy's leaving their drive thru window open until 1am, and some mcdonald's staying open 24 hours a day, and you have walmart open 24 hours a day.  These are fairly new business schedules.  Is that because the nation is becoming populated enough that it can support the store being open those times?  Maybe that mixed in with business' wanting to meet a higher demand for alternative lifestyles?  Perhaps more and more people are working different hours instead of the 9-5.  If this trend continues, I'm seeing movie theaters being open 24/7, malls open 24/7, and anything else you can think of.  And as society makes it easier and easier for people to live alternative schedules, perhaps you'll have people, like myself, being less inclined to be awake during the day, to function as "normal people" do.  Maybe one day, the night crew will be so many, that there truly will be a nation of night crawlers and day walkers.  Completely separate in culture, thinking, social constructs, and skin tone.  What happens to a nation that doesn't sleep?