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How To: Create a region map without internal boundaries using the Dissolve tool in ArcToolbox

Summary

Instructions provided describe how to create a region map without internal boundaries using the Dissolve tool in the Data Management > Generalization toolset. The article uses the 'states' theme found in the arcgis\Bin\TemplateData\USA directory as an example. In this example, U.S. state boundaries are removed, but regional boundaries (Pacific, Mountain, etc.) are retained and the regions are symbolized.

Note:
This article does not address region polygons. See the ArcGIS Desktop Help for more information.

Procedure

Create the region map by dissolving the features based on an attribute in the theme table. Dissolving combines all the features with the same value into one feature without internal boundaries. The 'states' theme in this example uses a Sub_region field to dissolve the features.

  1. Add states.shp from the C:\program files\arcgis\bin\template data\usa directory to the data frame.
    [O-Image] States Before Region Dissolve
    Note:
    For version 10.x, the states layer is in a file geodatabase that can be found in the C:\Program Files(x86)\ArcGIS\Desktop10.x\TemplateData\USA feature dataset

  2. Open ArcToolbox.
  3. Select Data Management Tools > Generalization > Dissolve.

    Note:
    An ArcInfo license is necessary to work with coverages and to use the Dissolve tool in the Coverage Tools > Data Management > Generalization toolset.

  4. Select states.shp as the input features to dissolve.
  5. Check Sub_region as the attribute to dissolve.

    Note:
    Multiple fields can be used to dissolve features.

  6. Click the browse button next to the Output Feature Class to name and save the output feature class.
  7. Optionally, select other attributes to summarize, and click OK.
    [O-Image] Completed dissolve tool 9.0
  8. Symbolize the 'states' theme with unique values based on the Sub_region field.

    A. Right-click the states layer and select Properties.
    B. Click the Symbology tab.
    C. Click Categories from the Show list on the left side of the dialog box to select Unique values.
    D. Select Sub_region from the Value Field dropdown list.
    E. Select the color scheme or the colors to use for each region.
    F. Click Add All Values and click OK to close the Layer Properties.


    [O-Image] Unique Symbol tab

  9. The final result should look similar to the image below:


    [O-Image] States after region, ArcMap
    Note:
    For more information about the Dissolve tool, type 'Dissolve tool' on the Index tab of the ArcGIS Desktop Help.