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General Category => Map Making Support => Topic started by: dhulting on April 28, 2009, 11:27:13 AM

Title: County Lookup on Latitude, Longitude
Post by: dhulting on April 28, 2009, 11:27:13 AM
Is there a way to get the county of a latitude, longitude pair?

tia
Title: Re: County Lookup on Latitude, Longitude
Post by: -Oz- on May 07, 2009, 06:19:10 PM
For what purpose, a web program or what?

The map i made the one above started out as polygons so I can easily pass that to you if that would help.
Title: Re: County Lookup on Latitude, Longitude
Post by: dhulting on May 08, 2009, 08:53:24 AM
That would be awesome! I have sales people listed by counties, and I'm trying to pair them up with geocoded locations of prospects (lat/lon). County data is tough to extract. The polygon solution sounds promising.
Title: Re: County Lookup on Latitude, Longitude
Post by: maps4gps on May 08, 2009, 11:53:16 AM
If you do not have to many, Global Mapper will let you load up to 4 files (for free).  Open a State's county polygon file from Census and your coords as a .gps, csv or ascii file and match one at a time.  With a GIS program($$$$) the match could probably be done automatically.
Title: Re: County Lookup on Latitude, Longitude
Post by: -Oz- on May 10, 2009, 06:08:49 PM
county shapefiles (polygon): http://www.gpsfiledepot.com/uscounties.zip let me know once you've downloaded it so I can clear up the space...
Title: Re: County Lookup on Latitude, Longitude
Post by: leszekp on May 10, 2009, 11:00:50 PM
One way you could handle this is to convert the geocoded coordinate pairs to a point shapefile with the free GIS MapWindow:

http://freegeographytools.com/2007/a-free-and-easy-shapefile-coordinate-converter

Then use the county polygon shapefile, the coordinate point shapefile, and MapWindow's Identity of Shapes With Polygon function to determine which county each point lay in:

http://freegeographytools.com/2009/assigning-attributes-from-a-polygon-shapefile-to-another-shapefile
Title: Re: County Lookup on Latitude, Longitude
Post by: Indrid Cold on May 18, 2009, 11:23:01 AM
Quote from: leszekp on May 10, 2009, 11:00:50 PM
One way you could handle this is to convert the geocoded coordinate pairs to a point shapefile with the free GIS MapWindow:

http://freegeographytools.com/2007/a-free-and-easy-shapefile-coordinate-converter

Then use the county polygon shapefile, the coordinate point shapefile, and MapWindow's Identity of Shapes With Polygon function to determine which county each point lay in:

http://freegeographytools.com/2009/assigning-attributes-from-a-polygon-shapefile-to-another-shapefile
Even better!
Title: Re: County Lookup on Latitude, Longitude
Post by: dhulting on May 18, 2009, 11:33:22 AM
Thanks a mil for the solutions! When I can get back to thisproject, I'll take these for a spin.