How do I convert a non-closed line (think of it as a C) to a polygon filling the area in ArcMap?

I think I can convert a ring to a polygon with the Construct Polygon function on the Advanced Editing Toolbar. However I get the following error: "No polygons were created. Ensure the selected features form continuous rings and overlap the polygons."

Obviously, I need to make my C into an O. It's just a matter of adding a line segment between the two endpoints. How do I add that segment and make the line into a ring?

  • 2
    How good are you at python, VB.net or C#? You could fumble through it by feature vertices to points (both ends), add XY coordinates, export to a table then points to lines to close the gaps by going directly from start-end (or end-start) but this would be a lot better with code.. if you have some please post it. May 30, 2018 at 1:19
  • 1
    Make it an answer perhaps?
    – Joooeey
    May 30, 2018 at 1:27
  • 2
    If my comment has helped you come to an answer feel free to expand with your methods, pictures and links to answer your own question and I'll upvote it. May 30, 2018 at 1:46
  • 2
    Convert line to vertices, points to line (close), result to polygon. Script is a last resort.
    – FelixIP
    May 30, 2018 at 3:54

1 Answer 1


A manual solution was suggested by Michael Stimson in a comment to the Q:

  • Use Feature Vertices to Points (Data Management) to convert the line into a list of points
  • Use Points to Line (Data Management) and tick Close Line to get a ring.
  • Activate edit mode by clicking Editor > Start editing on the Editor toolbar. Select a target layer that supports polygons. This does not have to be the source layer with your ring (line).
  • Select the ring and convert it to a polygon with the Construct Polygon function on the Advanced Editing toolbar.

I accessed the first two functions from the search button which is usually on the right of the screen.

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