Dissolve boundaries

For an upcoming analysis project, you need a layer that maps the districts in the Kyushu region of Japan. Japanese districts, or gun, are similar to counties, but they only exist for rural areas and are not used for any governing functions. You were not able to find data that maps districts. However, you did find a layer mapping municipalities. Because districts are composed of multiple municipalities, you can use this layer and the Dissolve Boundaries analysis tool to create the data that you need.

This tutorial was last tested on November 24, 2023.

View final result

Requirements

• ArcGIS organizational account with a Publisher, Facilitator, or Administrator role in an ArcGIS organization (see options for software access)
• 0.156 credits

Dissolve boundaries

Video

This tutorial is also available as a video.

Dissolve boundaries video

Filter the data

You'll start by filtering the Kyushu Municipalities layer to only those municipalities that also have a district name.

1. Open The Kyushu Municipalities web map.

   A map appears, showing all of the municipalities in the Japanese region of Kyushu.

   

2. If necessary, on the ribbon, click Sign In and sign in to your ArcGIS organizational account.

   Note:

   If you don't have an organizational account, see options for software access.

3. On the Settings (light) toolbar, click the Filter button.

   

   Note:

   If the Filter button is unavailable, in the Layers pane, click Kyushu Municipalities. The Filter button is only available when a layer is selected.

4. In the Filter pane, click Add expression.
5. Under Expression, click the first menu and choose 郡名 (District). Click Replace.
6. Click the second menu and choose is not blank.

   

   The map filters to only show municipalities that have district names.

   

7. Click Save.

   There are only 53 districts in the Kyushu region, but the layer still shows 156 features. Depending on your purposes, this might be OK. However, for your map, a filter will not be sufficient because you need to label the districts and you only want to show one label per district. For this, you need each district to be stored as a single feature.

   Next, you'll create a layer that only has 53 features, one for each district.

Dissolve boundaries

The Dissolve Boundaries tool finds polygons that overlap or share a common boundary and merges them. You'll use this tool to merge all municipalities with the same district name.

1. On the Settings toolbar, click the Analysis button.

   

   Note:

   If you do not see the Analysis button in Map Viewer, contact your ArcGIS administrator. You may not have the privileges required to perform analysis.

   Learn more about licensing requirements for spatial analysis.

2. In the Analysis pane, click Tools.
3. Expand the Manage data section and click Dissolve Boundaries.

   

4. For Input features, click Layer and choose Kyushu Municipalities.

   The layer appears in the tool pane with the message Count of features: 156. Only the filtered features will be used as inputs in the tool.

   

   Note:

   You could apply the filter after running the Dissolve Boundaries tool, but it is advantageous to apply the filter first: the tool will run faster and it will cost fewer credits.

5. For Dissolve settings, enable Dissolve features with matching field values.
6. Under Fields to match, click Field. In the Select fields window, click 郡名 (District).

   

7. Click Done.

   All municipalities with matching district names will be merged.

8. Ensure Create multipart features is turned on.

   Some districts in the Kyushu region extend over multiple islands. Creating multipart features will ensure that an area is considered one feature even if it consists of two unconnected parts on different islands.

9. Leave Calculate statistics for dissolved features turned off.

   This option is useful when the input features have numeric values that should be summarized. The Kyushu Municipalities layer has one numeric field—Area (km2)—but summarizing it is unnecessary because the Dissolve Boundaries tool always creates and calculates a new area field.

   

10. For Output name, type Kyushu Districts, followed by your name or initials (for example, Kyushu Districts Your Name).

    Note:

    You cannot create two layers in an ArcGIS organization with the same name. Adding your initials to a layer name ensures that other people in your organization can also complete this tutorial. Once a layer has been created, you can rename it in the map to remove your initials, which will not affect the name of the underlying data layer.

11. Click Estimate credits.

    

    The Dissolve Boundary tool will use 0.156 credits. The number of credits is based on the number of features to be processed.

12. Click Run.
13. At the top of the Dissolve Boundaries pane, click the History tab.

    

    You can see the tool's progress here.

    When the tool is complete, a new layer appears on the map.

    

Review and label the new layer

The new layer is partially transparent, so the municipality boundaries are visible underneath. You can see that multiple municipality polygons were merged to create single district polygons.

1. On the Contents (dark) toolbar, click Layers.
2. In the Layers pane, point to the Kushu Municipalities layer and click the Hide layer button.

   

   The municipality borders disappear from the map.

3. On the map, click some of the southern islands.

   Multiple polygons are selected as a single feature. These are multipart features.

   

   A pop-up appears, listing three fields. A field with the area of each district has been calculated. The Count_ field lists the number of features from the previous layer that were combined to make the selected feature. This is the same as the number of municipalities in the district.

4. Close the pop-up.

   Next, you'll label the map.

5. In the Layers pane, ensure that the Kyushu Districts layer is selected.
6. On the Settings toolbar, click the Labels button.

   

7. In the Label features pane, click Add label class. Ensure that Label field is set to 郡名 (District).

   Labels appear on the map with the name of each district. Only one label appears for each district.

8. Click Edit label style.

   

9. Click the first Color menu. In the Select color window, for Hex, type 001799 and press Enter.

   

   The labels change to a blue color.

   

10. Click Done.
11. Close the Label style window and the Label features pane.
12. On the Contents toolbar, click Save and open and click Save as.

    

13. For Title, type Kyushu Districts. Click Save.

You now have a feature layer that maps districts in Kyushu. Each district is a single feature. This is convenient for visualization—for example, you were able to create clearer labels for the map—and will be necessary for the analysis that you plan to perform with the data later.

In this tutorial, you learned how to filter a layer, how to use the Dissolve Boundaries analysis tool to merge polygons based on an attribute, and how to label features on a map.

You can find more tutorials in the tutorial gallery.

Acknowledgements

• The Kyushu Municipalities layer is derived from 平成 27 年国勢調査 市区町村界 - Japan Municipality Boundaries ECM: Esri Japan, Statistics Bureau of Japan.
• Human Geography Map sources: Esri, HERE, Garmin, FAO, NOAA, USGS, OpenStreetMap contributors, and the GIS User Community
• World Hillshade sources: Esri, Airbus DS, USGS, NGA, NASA, CGIAR, N Robinson, NCEAS, NLS, OS, NMA, Geodatastyrelsen, Rijkswaterstaat, GSA, Geoland, FEMA, Intermap, and the GIS user community