Where did deep-dish pizza originate?

I had a Chicago deep dish in Vancouver once in a restaurant at the corner of Smithe and Hamilton that of course is not there anymore, that was so thick and heavy, it took both hands to hold it and a super open jaw to eat it. Each piece felt like a pound and you could only really eat one or one and a half pieces. It was a good night from a long time ago...

Illinois has the best pizza hands down