Miss America prelims have a sorority twist!!
 

http://www.missamerica.org/lineup/lineup.asp

Check it out...the contestants are divided into 3 groups, Mu, Alpha and Sigma.
I surmise that it is to correspond with the full name, The Miss America Scholarship Organization...

Mu=M=Miss
Alpha=A=America
Sigma=S=Scholarship

Homepage is here... http://www.missamerica.org/