Source: National Climatic Data Center.
We published a more serious graphic today on drought’s effect on crops, but this was a fun animation we made to sanity-check parsing drought data. NOAA publishes monthly values for the Palmer Drought Severity Index going all the way back to 1895! Dark purple represents extreme drought, while dark green represents extreme moisture. In effect, this is a crazy electric version of Haeyoun Park and Kevin Quealy’s graphic, Drought’s Footprint.