According to the Iowa State Greek History Timeline (have you ever read it, it's so interesting!), the Pi Phi chapter at Iowa State was originally their Mu chapter, but became Iowa Gamma when the Fraternity restructured their chapter naming system.

According to the same timeline linked above (and the Bairds on Google Books), the first Delta chapter of Delta Delta Delta was founded at Iowa State University, but due to campus unrest, did not last long. They are known as Omega Delta now. But a proper History as published by Tri Delta would be the best source.
The Delta chapter of Kappa Kappa Gamma (our oldest continual chapter) is on the main campus at Bloomington.

Yup, when they reopened the USC chapter they named it Alpha Nu instead. I'm not sure why they didn't call them Delta chapter again, but the single letters were definitely not done in a logical order (ie, Alpha, Beta...). Maybe the second USC was a different local and they wanted to honor that? If I find out why, I'll post again. Or maybe one of the other DGs here knows.

IIRC, Sigma Kappa's first three chapters all being at Colby had something to do with limiting the initial chapter size to so many members.

I have read it, I love history. I don't know how I missed the part about Pi Phi, I think I'd seen so many references over the years to them being the Iowa Gamma chapter that I didn't even think about it.

Yep, originally Sigma Kappa limited the number of members in a chapter to 25. As the number of women at Colby grew (they wanted to include all of them!) they added first Beta then Gamma chapter. Finally they decided to close Beta and Gamma and fold the membership into Alpha. (The chapters met together often anyway.)

See, this is why I think it's better for someone to do it alphabetically instead of a member of each sorority posting a list. You learn so many interesting things!!! :)

Exactly, stop all of this fussing and fidgeting.

Lets do it by letter. It would be more fun that way.

In the "History of Delta Delta Delta 1888-1988", Iowa State is listed as being open as the Delta Chapter from 1980-1982. The chapter was reestablished in 1912. Tri Delta was petitioned by a local sorority called Omega Delta and since Delta was now Simpson College; they were allowed to keep the local name. Simpson's chapter was installed as Delta Deuteron in 1897 but was changed when the Iowa State chapter closed.

My books finally came in handy :)

I certainly appreciate all of the non-Chi Omegas trying to understand/explain our system for naming chapters -- believe me, there are plenty of Chi Omegas who can't understand it! ;)

I'll try to make this simple:

Look at the Greek Alphabet from end to beginning (always leaving off Omega, as that is for deceased members). Psi is the first chapter...proceeding through single letters until Alpha.

Next, repeat the backwards alphabet again, this time using the second letter "Alpha" ...Psi Alpha, Chi Alpha...until Alpha Alpha.

Next group begins with Psi Beta, Chi Beta...until Beta Beta.

There are a few exceptions, but basically -- that's it!

Buttonz, with all the purple text, I think you are the Grapist! ;) :) Fess up!! :D:p

Wasn't that Delta Sigma? The only group AOII ever absorbed.

yup - and Gamma (Maine) and Delta (Tufts) chapters are celebrating their centennials next year.

Isn't there a Beta Alpha (UPenn)? I have a friend who joined Chi O there.

So there are no Omega Psi, Omega Chi, Omega Phi, or just no Omega?

Do the groups end with the double letter (i.e the _____ Gamma series stops with Gamma Gamma)?

There are no Omega chapters whatsoever. Omega is for departed sisters.
No, the chapters can end in the same letter and keep going. For example, we have a Delta Delta chapter at Cal-Santa Barbara, Alpha Alpha, Theta Theta and a few others. And yes, there is a Beta Alpha.