Ok so I've been watching numerous bikers here in Chicago riding by with no semblance of a helmet anywhere. On further enquiries, I found out that riding with a helmet is not mandatory in the state of Illinois. What I was told is that they have done research on this and found that if you have a fall above 40 mph, it is going to be fatal anyways even if you ride with a helmet and that you will be riding at over 40 most of the time. Plus, trying to get a person who has survived a fall, out of his helmet before transporting him to the nearest hospital, is difficult and so they have gone with the no mandatory helmet rule.
For more, check the attached link http://bikersrights.com/states/illinois/illinois.html The Illinois Supreme Court has ruled that the law making helmet wearing mandatory was unconstitutional.
I feel like Obelix - tapping my head and saying "These Americans are crazy...."