What is this? The study looked at references in Google Maps for a given geographic area, a series of connecting concentric circles. It compared references to "grocery store" and to "bar"; if there were more references to grocery stores within that geographic circle, it colored the circle yellow, if there were more references to bars, it colored the circle red. It's important to know that there is no shading here, so whether there was 1 more reference or 50 more references cannot be determined. You will notice that Wisconsin is the only state that is almost entirely red.
So, what does that mean? Well, it means we have a lot of bars as compared to grocery stores. Making some logical assumptions it means that we drink outside of the home (at a bar) more than we drink inside the home (grocery store). It also means that we have to drive home from bars. So, it's no surprise that we lead the nation in DUIs. Here's the graph from 2008 of the nation's highest reported DUI:
Wisconsin MSAs v North Dakota MSAs. MSAs in Purple and some of the darker gold are considered MSAs as well.
So, what does that mean? Well, about 2/3rds of Wisconsin residents live within the geographical type most likely to drink and drive - Small Metropolitan Statistical Areas. While only 1/2 of North Dakota residents do. This difference in population gathering alone could account for the vast majority of the difference between Wisconsin's DUI rates and North Dakota's despite similar concentrations of bars.