I think it's hard to compare to rent in Chicago to rent in Toronto and make too much of a judgement about it. The cost of locating in one place includes rent, property taxes, income taxes (some states have no income taxes and simply levy their income through property taxes), but it also includes other things like government subsidies and a lot of nebulous things such as whether or not you can get highly qualified people to live in the neighbourhood of your office. For instance, I'm sure the office rental costs for Cincinnati are rock bottom, but getting people to live there is difficult.
As well, we are talking about two different countries with completely different economies. Chicago isn't really competing directly with Toronto for a lot of jobs - it's competing with New York and cities in the Midwest. There is some overlap, but as I know from my work in a multinational, Toronto offices rarely cover work that involves Americans. Some low-end office work (like call centres) is outsourced to Canada, but generally to (relatively) low-cost, high-education places like Montreal or Winnipeg. All of the high-end stuff usually remains in America.
I think it's fun to compare the office markets with Chicago, but in the end we have to take any conclusions with a grain of salt.