[5] To avoid losing profits, ten bars in Champaign's Campustown, including several owned by Scott Cochrane, held a Saint Patrick's Day-themed event called "Shamrock Stagger" on March 8, 1995, two days before the university's spring break.

[2] The following year, in 1996, presumably after pushback from the university, events held at Cochrane-owned Campustown bars the week before spring break were advertised as "Unofficial Saint Patrick's Day" for the first time.

[12][13] In 2017, 23-year-old university student Jonathan Morales, a junior majoring in communications from Franklin Park, Illinois, fell over the railing of a fourth-floor balcony during an Unofficial party.

[13] Other negative consequences of Unofficial have included vandalism of university bathrooms, disruption of classes, an uptick in parking violations on campus, and a significant increase in tickets and arrests, especially for underage drinking and drunk driving.

[2][12] Campustown sees heightened police presence during Unofficial, including officers representing the university, the cities of Urbana and Champaign, and the state of Illinois.