Projection Help GPS vs National Atlas

James Goddard james at GODDARD.BZ
Tue Mar 29 15:20:06 EST 2005

I'm a little confused by all of the projection stuff.  Any help would be

I'm using the National Atlas maps from

I am able to get the layers I want displayed great.  Now what I want to do
is add a layer of GPS points.  I am creating a shapefile for these points
with shapetools entering decimal lat/lon positions.

When I display this layer it the points display but are way off of the US

I've been playing around with the projections and have yet to figure out
what I need to get this to display correctly.  Here is what I have:

#main mapfile projection
"proj=lcc" "lat_1=32" "lat_2=44" "lat_0=38" "lon_0=-
100" "x_0=0" "y_0=0" "ellps=GRS80" "datum=NAD83"

#National Atlas layer projection
"proj=latlong" "ellps=GRS80" "datum=NAD83"

What projection should I use for the GPS coordinates so that they display


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