I think it depends on the university. I know that not all 9 NPC groups at Ole Miss (Chi Omega, AOII, Tri Delta, Phi Mu, Kappa Delta, Kappa Kappa Gamma, Kappa Alpha Theta, Pi Beta Phi, & Delta Gamma) are "southern" sororities (meaning they were founded in the South. I think there is a thread on here somewhere about that.
I think Phi Mu and ADPi might have more chapters at some of the more southern universities and colleges. However, ADPi left Ole Miss in like 1995. Tri Delta is HUGE in Mississippi at all of the schools and they were started at Boston University in 1888. AOII has chapters at ALL SEC schools except Miss State, LSU, Arkansas (Coming 2006!), & South Carolina---So I think it depends on the chapter itself and the school!
Edited to add Kappa
