I have never seen graffiti of any kind in my IL town, yet you find this huge collection in your area. Very strange.
I don't think you venture into the correct areas of the city Phyllis. Head into some different burbs with a higher latino population. You are sure to find some there. They paint some of the best stuff here. Or just head into the known "colourful" parts of of the big city. I used to live in Waukeegan and North Chicago and I can remember lots of graffiti around. Could'nt keep it off the buildings in NC. I have another area scoped out I want to shoot next. Hopefully before it gets to freezing here. Head over by the Great Lakes Naval Base you will be sure to find some if you can't find any anywhere else.
PS...You know where I live anyway, I have told you before. It's less than an hour from you. I'll be careful and thanks.