[GRASSLIST:3015] RE: [gislist] US cities and counties

Martin du Saire mdusaire at umn.edu
Tue Mar 23 09:59:40 EST 2004

Hello again,

As I mentioned, I am compiling corn yield data for the grain belt US based 
on county-wide data for about 14 states.  Eventually I will need to plot 
these data to analyze yield spatial distribution.  So I need to be able to 
assign these county production values to some location, probably the 
geographic center of each county.

One of the goals is to calculate a center of mass for production.  The 
region of interest spans:

Lat: 35N to 49N
Lon: -104 to -80

The question is how to choose a projection that will allow me to calculate 
a reasonable (yet to be determined what will be considered reasonable) 
estimate of center of mass.  I am considering Albers Equal Area, 
Equidistant Conic, Azimuthal Equidistant, and Two-Point Equidistant.  (I am 
using GRASS, and I think TPE is not supported).

Thanks again for your help.


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