The February 1-2, 2011, blizzard crossed through much of central and northern Illinois. By overlaying the snowfall map over the 2000 Census data using GIS software, we can estimate the number of people in Illinois affected by the storm. A rule of thumb in winter storms is that economic impacts become significant in areas with 6 inches or more of snow.
From the map, about 10.9 million Illinois residents were in areas with 6 inches or more of snow in the February 1-2 storm. Furthermore, about 9.8 million Illinois residents were in areas with 12 inches or more of snow. And about 1.5 million Illinois residents were in areas with 18 inches or more of snow.
Disclaimer: all snowfall totals that went into this map are preliminary and subject to change. The census data are from 2000 and may not reflect current population levels.
Fantastic map and a brilliant use of GIS! Great job, Zoe!