UW has Mifflin Street, Illinois has Unofficial. This year it fell on this weekend.
The event is actually Unofficial St. Patrick's Day because apparently it usually works out that the spring break here is around St. Patrick's Day. That's not the case this year yet people had it anyway.
Naturally it isn't as big as Madison's Halloween or Mifflin Street, but there are still people house and balcony parting and all the bars on the restaurant street near campus overflow with people in green. On the local tv news, they were interviewing non-local people. Some had come Iowa.
Here's what the student newspaper says about it. And another article--the police are clamping down on students here as well at these sort of events. Here's the local newspaper's take. (Both sites have pictures.)