I live in an area that was settled in the 1790's so there are a lot of century old or older homes. As I drive around I can't help but notice the number of older home--75 yrs or older--that have small structures sitting out back--some have been converted to playhouses or garden/storage sheds, other are slowly disintegrating. If you look closely at them you'll see tell-tale signs they once housed chickens--roof vents, chicken doors, etc. While these are more common in the smaller towns you will see them in the older sections of the cities where the lots were once fairly large. Often too, there may be no shed but the is a barn/stable which, again if you look closely, had a part reserved for the family's flock. The point is that raising a backyard flock is part of our heritage, something the makers of "no chicken" laws seem to forget. I remember as I was growing up in the late40's/early 50's many still had small, self-sustaining flocks--a rooster, laying hens and a broody with next year's chicks where extra roos and old hens became Sunday dinner. So I guess those that are keeping backyard chickens are just retros. BTW, there are, increasingly, more of those old coops that are being reconverted to or replaced by chicken coops.