Environmental Factors=Stunted Growth?

Call me crazy, but I've noticed a lot of short (and I'm classifying short as 5'5" and under) people in New York.  And not one specific group either.  I see short people of all colors, races, and, ethnicities.  On any given day, when I'm in the elevator at work, I often tower over others in the car and my height is average (5'7"), or at least what I thought was average.  I am seriously starting to wonder if there are environmental factors that have stunted the growth of many New Yorkers.  Is there something in the air or the water?  When I lived in Philadelphia and Detroit, I never noticed an overabundance of the vertically-challenged.  But in New York, I can't help but notice it.