I've observed that usually where a sorority is founded has the highest concentration of chapters, and it kind of branches out from there. For example, Delta Zeta was founded in Oxford, Ohio, so we've got lots of chapters around the Ohio area, and we spread further in all directions as the years passed.
Another example: Phi Mu and ADPi were founded in Macon, GA (my hometown), so the majority of their chapters are in the Southeast, although they too have spread out through the years. When I got to school, DZ, Phi Mu and ADPi were the only 3 sororities on campus and Phi Mu and ADPi were the two that rushees were most familar with because they are the "southern" sororities, as opposed to Delta Zeta which is more of a "northern" organization. I'm sure that the tables would be turned up North with rushees not knowing much about Phi Mu or ADPi, but being pretty familar with Delta Zeta.
So, I guess that there isn't one area that has a large concentration of all GLO's -- more like one area that has a large concentration of a few particular GLO's. Does that make sense?
Hope this helps!
