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How To: Edit the common boundary of polygons from different shapefiles

Summary

Sometimes a map contains features that share common boundaries. For example, an electoral map showing electoral district boundaries, a geological map showing multiple geological formations, or a world map showing country borders. When editing a map with common boundaries, moving a shared boundary simultaneously ensures the features with shared geometry are seamlessly integrated without gaps in the merged feature class.

The map below shows two federal territories (Kuala Lumpur and Putrajaya) and two districts in the state of Selangor (Petaling and Hulu Langat) in Malaysia, which are adjacent to each other. These different shapefiles are merged and subjected to map topology to ease editing or boundary refinement.

This is the map of adjacent federal territories and state districts.

Procedure

The following workflow describes how to edit the common boundary of polygons from different shapefiles:

  1. Combine multiple shapefiles into the same feature class using the Merge tool.
    This is the Merge dialog box.

    The following image is the feature class generated after merging the shapefiles.

    This is the output feature class of merged shapefiles.
     
    1. In ArcMap, click the Search button, and type Merge in the search box.
    2. Click the Merge (Data Management) tool. This opens the Merge dialog box.
    3. For Input Datasets, select all the layers to merge from the drop-down menu. The Output Dataset is automatically generated once the Input Datasets are specified.
    4. Click OK. A merged feature class is generated.
  2. Subject the newly created feature class to map topology. This enables the features in the selected layer to be edited simultaneously.
    1. Enable the Topology toolbar by navigating to Customize > Toolbars > Topology.
      The Topology toolbar appears.

      This is the Topology toolbar.
    2. Right-click the merged feature class created in Step 1, and click Edit Features > Start Editing.
      This automatically enables the Topology toolbar.
    3. Click the Select Topology tool This is the Select Topology tool.. This opens the Select Topology dialog box.

      This is the Select Topology dialog box.
    4. Click the Map Topology option and select all the layers to include in the map topology.
Warning:   
Ensure all the layers for editing are enabled (visible). This is important because topology editing on an enabled layer does not automatically update the geometry of the disabled (hidden) layer. 
  1. Click OK.
Note:
The Cluster Tolerance field under the Options section specifies the default value of the distance that ArcMap considers coincident. The default value is the minimum possible value. Increasing this value results in more features considered as coincident.
  1. Edit the common boundary of the layer subjected to map topology.
    1. Select the Topology Edit tool.
      This is the Topology Edit tool.
    2. Select the line segment for editing.
    3. Click the Modify Edge tool This is the Modify Edge tool.. The Edit Vertices toolbar opens and nodes appear along the selected line segments for editing.
      This is the Edit Vertices toolbar.
    4. Select and move the vertices to edit the boundary.
      Nodes appear long the line segment chosen to be edited.
    5. Click Save Edits to save and end the edit session.
Warning:   
Using tools other than within the Topology toolbar (for example, using the Editor toolbar) to edit a common boundary causes the coincident boundary to be lost. 

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