Small towns USA

Mark and I try to stay off the interstate as much as possible.  I'm not saying that we drive through all small towns, but I started noticing the city limit signs.  Boyd-618, Wheeler-758, Firewood-528, Ridgeland-237, and Downing-265.  There were more, but you get the idea.  When I see these signs, I wonder whose job is it change the numbers on the sign.  How often do they change the numbers, who counts and do they change it after ever birth or death.  I love small town America.