What’s intriguing about this 1931 map is how much beer they’re still drinking in the Rust Belt during Prohibition. That map would track reasonably well with a map of today.
But after nearly a decade of temperance, why all the beer? As a drug, it’s inferior to liquor or wine because the lower proof means lower street value. As contraband, it’s harder to smuggle because it takes up more mass. Distribution is difficult because, well, how many bottles of beer can your average scofflaw walk away with? Otherwise they have to consume it on site, at the speakeasy or wherever. Maybe there were advantages in brewing speed? More turnover = greater profit?
Looking at this map you’d think Prohibition had practically no affect on drinking habits at all. Funny, that.