Phone numbers are an amazing way to track the growth of a population. Even when I got to Chicago, things were still kind of handleable; everyone had a 312 prefix. Then they split the city and suburbs apart with 312 and 847; then they had to split the city into downtown and non-downtown: 312 and 773 (which prefix we now have, because yes, we still have a land line of sorts), while the burbs got split between 847 and 630. Then mobiles happened and they got 630 prefixes as well as 229 prefixes ... oh, the snowballing complexity of it all! Heh.