Fraternity Campus Overlap
 

Since the sorors have one, I'll start the fraternity one.

I think SAE and Sigma Chi are at the same universities often.

We have a lot of chapters at small schools, and I noticed there is often a TKE chapter at that school as well.

I think it just depends on a fraternities expansion policy. I know Phi Gamma Delta tries to establish chapters at large and/or highly regarded academic institutions with a strong greek system. While other fraternities may have a different policy (most chapters possible, strength within a certain region, etc.) It all comes down to an international fraternities preference.

Overlap
 

I'd have to guess DU overlaps with Beta more than any other organization.

Virginia Circle
 

There's something called The Virginia Circle. I don't think anyone ever intended it to happen, but we all do seem to meet each other on many, many campusses. These are the six fraternities founded in Virgina: Pikes, Kappa Sigma @ UVA; Kappa Alpha Order @ W&L; , Alpha Tau Omega, Sigma Nu @ VMI; and Sigma Phi Epsilon @ Richmond.

Re: Virginia Circle
 

Wow...we have all of them except Kappa Sigma and Sigma Phi Epsilon. That's really cool.