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Cartographic Data Needed

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  • Cartographic Data Needed

    Hi folks. Not sure where this question best fit in, so at risk of posting in the wrong place....

    I'm looking for some free (or pretty cheap) cartographic data. I have a project in mind to create images of the 50 states and color them in by county, the colors representing some kind of data. Ideally the mapping data would give enough data to draw a polygon & color it appropriately for each county, based on input data from a file.

    I can see making up the data by hand for, oh, Delaware, but Texas would near kill me. Rough approximations would be fine, it's just for display purposes.

    I sent a similar question to the USGS today too.

    I did find some sites that had huge databases of map stuff for sale, but I don't want to spend hundreds for just a little piece of that. Any clues to where else I might look?

    The boy just ain't right.

  • #2
    Many, many years ago I got a CD from USGS. It had a lot of mapping data, but at this distance I do not remember specifically if it addressed your case. However, my recollection is that the cost was relatively in-expensive. If you're close to one of their regional offices it might be worth the trip to see first hand ... since they stock some materials there and you'd not be waiting for the mail.
    Rick Angell


    • #3
      Maybe this will help...

      I'm not sure if this is exactly what you're looking for, but for one of our recent projects
      we were in need of shapefiles for each U.S. county and finally found them here:

      To download the shapefiles for a given state:
      1) select a state, then click "Submit Selection"
      2) select "County 2000" from the "Select by Layer" dropdown, then click "Submit Selection"
      3) select the "All Counties" checkbox, then click "Proceed to Download"
      4) click "Download File"

      This will download a ZIP file for the selected state containing a directory for each county
      in that state. Inside each directory is the county .shp file, .shx file, and .dbf file.

      Let us know if this helps!
      Thank you and God bless,
      Noble D. Bell


      • #4
        Thanks for the tips.

        The ERSI shapefiles look like what I need. But there's way more than I need for my app. I guess I'm going to have to dig in and extract the polygons.

        I'm thinking my shape data would look like:
        state (2 bytes): "CA"
        county_code (3 bytes): "001"
        county_name (40 bytes): "Alameda ... "
        Vertex_count (long): 20
        x & y data (lat/lon?) (doubles)

        next county

        next county

        next state
        The boy just ain't right.