If you try combining the *unprojected* county and zipcode maps, and plotting them with gplot (either drawing them with lines using interpol=join, or even just plotting as scatter plot points), do the two maps seem to line up? Also, you might want to specify the projection parameters on both the county and zipcode maps, to make sure they're projected exactly the same (if no parameters are specified, then gproject picks default values, based on the min/max extents of the map points it is projecting). As an alternative to *guarantee* that the 2 maps are projected using the exact same parameters, you could combine the two maps, and project them together, and then separate them again. Here is an example where I use proc gmap to draw the zipcode map, and annotate to overlay the county outline: http://robslink.com/SAS/democd69/wake_county_demographics.htm http://robslink.com/SAS/democd69/wake_county_demographics_info.htm ... View more