Read.
https://hawkstosox.wordpress.com/2015/10/19/chicago-marathon-2015/

This was the best race I've ran in terms of support, organization, just about everything. Of course, being a World Marathon Major, it should be. This was a race I've thought about running for a very long time, and I'm still excited I had the opportunity. It was a once-in-a-lifetime experience! Absolutely recommend anyone that has the ability to run it apply for the lottery and hopefully get that chance.