It is not in the nation, i literally said in the big ten, and i am referring to when we were 12 teams.
You are correct that allot of it has to do with the amount that travel, but IU would bring even more to Purdue, were an actual rival, and not be nearly as bad as OSU or Michigan fans.
Ask most people that had to deal with Big Ten fans and most will say OSU or Michigan were the worst.
They would walk into the bar like they own the place, talk constant trash against you and your team, and be very disrespectful. More fights broke out with OSU and Michigan fans, and some of these years Purdue was really, really bad before Joe Tiller took over, so most Purdue fans didnt even care.
I am speaking from experience of having to work at bars and have the fans come to town. Really its not just me, we discussed it before OSU and Michigan games. It was very much dreaded.
And please dont think i am speaking to every single fan, that is impossible, just speaking to my experience bartending in the 90's from those fans as a group. Ofcourse there were many more good fans than bad at any school, just saying there seems to be more bad fans at OSU than any other school. (even if 80% are good fans, the 20% do ruin the experience for those of us that have to deal with the remainder)