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I have a shapefile of U.S. counties. I am interested in compiling a list of those that border each other.

In particular, I am interested in those that border each other but are in different states. For example, I am interested in knowing that Rabun County borders counties in North Carolina and which ones and not the counties in Georgia that it may also border.

I work with ArcGIS 10.1 and use ArcMap.

I see that there is a feature called Polygon Neighbors. However, I don't fully understand how to use it. I'm not sure what to put into the "Input Features" or how to proceed from here.

I would very much appreciate any help!

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I think that how Polygon Neighbors works is already well documented, but in your particular example, the steps to use could be:

  1. Run Polygon Neighbors on your shapefile, which presumably has polygons for each County with their State as an attribute. Make sure you specify both County and State as fields to be used in the Output Table
  2. Open the Output Table to select any rows where the polygon and its neighbor have the same value for State - and delete them.
  3. You should now have rows in your Table for only those counties that neighbor a County in another State
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do i do this for the entire united states as one shapefile? or, do i input 2 shapefiles at a time? in the latter, it would be a shapefile of say geogria (with its counties) and one of north carolina (with its counties) – user1690130 Oct 15 '12 at 1:41
Only one shapefile is input - could be counties for whole of US or if your focus is counties of Georgia, North Carolina and no other states then select these out into a new starting shapefile first. – PolyGeo Oct 15 '12 at 1:44
It sounds most efficient to just do two states at a time? Then I wouldn't have to do any of the deleting? – user1690130 Oct 15 '12 at 1:49
You would only be deleting records for counties adjoining other counties within the same state. – PolyGeo Oct 15 '12 at 1:53

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