How Airports Serve Iowa
Mark Pearson
This map displays the major airports in and around Iowa. It shows how the state can divided according to which airport is the closest as the crow flies.
The flags are a sample of 500 census tracts (of 823 tracts total) within the state.
Some census tract flags may look like they are colored for one airport's region but are actually in another airport's region. The census tract flags are colored with which airport they are closest to as the crow flies along the surface of the earth (the Haversine distance formula). The region boundaries that are displayed on map were computed assuming assuming the earth is flat. (The lines that divide regions are a Voronoi diagram, and I couldn't find any algorithm that calculate the lines on a sphere such as the earth.) In short, although a few census tracts may look like they're mislabeled near a boundary, it's actually the boundary that is slightly wrong.
For more information, see the full report:
http://www.mark-pearson.com/airport-distances/

DSM serves 1,066,595 people in IA
Des Moines International Airport

CID serves 894,120 people in IA
The Eastern Iowa Airport

MLI serves 364,159 people in IA
Quad City International Airport

OMA serves 277,242 people in IA
Eppley Airfield

FSD serves 241,775 people in IA
Sioux Falls Regional Airport (Joe Foss Field)

RST serves 158,597 people in IA
Rochester International Airport

LSE serves 43,867 people in IA
La Crosse Municipal Airport

dividing line

1,953 people
closest airport: CID

1,764 people
closest airport: CID

6,092 people
closest airport: CID

closest airport: OMA

closest airport: DSM

closest airport: FSD

closest airport: MLI

closest airport: RST

closest airport: LSE

376 people