* There are many other large venues in Chicagoland suitable for a rally with 10,000 people.
Why would the campaign pick the Pavilion, and once they did and saw signs of trouble why not switch to a different location well in advance of the event?
Bulls were playing at United Center.
Rosemont Horizon (Allstate Arena) had a Wolves match on Saturday. It it had been available, it might have been a better location.
Sears Centre is 25 miles from Chicago and barely even in Cook County.
The UIUC Pavilion is adjacent to an expressway, and only peripheral to the campus. The only university events it appears to host are basketball games for UIUC. Is south of the expressway a No Go area?
The Pavilion is adjacent to an expressway but it's right by one of the most notorious traffic bottlenecks in the Chicago expressway system. The Circle Interchange is so well known that UIC was once called UI Circle Campus.
The Allstate Arena would have been my first choice if I were advising the campaign. It's adjacent to O'Hare for the candidate's convenience, it's easy to reach from both the city and suburbs, it's easy to police. It's about twice the capacity of the Pavilion (18.5K to 9.5K) but I suspect that Trump could fill it.