It is true that the level of support are not the same. Also Assembly Hall at IU is a bit more centrally located than CHA on UofI's campus.
JM makes a good point about time of game and recent attendance at IU, however a point against Jon's rationale is the fact that compared to IU, CHA is incredibly easy and convenient to attend. Getting in and out of IU's sports complex as a commuter is pure hell, and it is a credit to IU fans for piling in year after mediocre year.
I have been back to CHA for basketball games the past few years, and still don't understand why attendance is as down as much as it is (ease of TV and the couch?), especially from the student's standpoint. Even in the lean years, I thought going to CHA was an incredibly fun and inviting atmosphere, where I felt very comfortable taking my young family, and just getting the heck out of the house for a night in a wonderful facility. I hope it picks up now that the program really does look like it has found the correct path in their new Head Coach, talent, and facilities. The game yesterday, for me, was a touch stone moment for my support of the basketball program. I was walking mighty tall in my Black and Gold last night in Indianapolis, and I'm only 5'9"...
Go Hawks.