Bars v. Grocers

Via reader AS, Floating Sheep analyzed the relationship between bars and grocery stores in the U.S. and Canada:

We had expected that grocery stores would outnumber bars and for most parts of North America that is the case. But we could also clearly see the "beer belly of America" peeking out through the "t-shirt of data".

Starting in Illinois, the beer belly expands up into Wisconsin and first spreads westward through Iowa/Minnesota and then engulfs Nebraska, and the Dakotas before petering out (like a pair of love handles) in Wyoming and Montana.

On average there are 1.52 bars for every 10,000 people in the U.S. but the states that make up the beer belly of America are highly skewed from this average.

I notice that Chicago has fewer bars than grocery stores, and I am confused. Chicago is the land of bars on every street corner identified only by Old Style signs and dirty windows. Maybe there are gypsy grocers no one sees lurking in the neighborhoods?