Pundits and politicians talk a blue streak about the dangers of inflation. But what do the rising or falling prices of illegal commodities like marijuana tell us? What lessons can we learn from the economic geography of underground economies and, well, weed?

Consider this fascinating analysis of the geographic variation in marijuana prices across the United States by the Floating Sheep collective of geographers. They find that weed prices range from a low of $256 per ounce for high-quality pot in Oregon to a high of $450 per ounce in Delaware (nationwide, the average price per ounce for high quality weed is $377.02; mid-quality herb can be gotten for $245.14; the average going price for schwag is $138.12). Floating Sheep built its database from the website PriceofWeed.com, which crowd sources the street value of marijuana from consumers, collecting and providing data on the retail prices of marijuana by quantity, quality, and location. Their database includes 16,502 price records from 2,397 US cities...