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For ArcMap10: I know there are multiple way to do this, but I wanted to see what was the most efficient for this case, as I will be doing it repeatedly in my workflow. I have a .shp polygon layer with multiple polygons within it. I need to change one polygon within this, and am simply dividing it into two pieces. They are property tracts, and one owner has sold half of his portion, now making it two separate tracts. So, the property tract is currently 1028, and needs to become 1028 and 1028A. I have thought of simply deleting, and re-drawing, but is there a more efficient way?

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  • I'm assuming that since these are property tracts that they will need to be split in a specific way to redefine tax parcels? Not just randomly splitting a parcel anywhere?
    – MaryBeth
    Dec 1 '15 at 14:31
  • Yes, Mary. This polygon is already physically split. So, it looks like two triangles and they are both labeled 1028. There is another polygon running between these ones. I need to simply recreate these two pieces so that one is labeled 1028 and the other is 1028A. Does that make sense?
    – Nathan
    Dec 1 '15 at 14:44
  • You may want to edit your question/title to reflect that you are actually looking to update an attribute or label, rather than cutting the polygon in two--I think many of us are thinking of ways to split and physically change the shape of your polygon, rather than update an attribute :)
    – MaryBeth
    Dec 1 '15 at 14:48
  • Well, I could just change labeling, but that will not make the polygon that is technically in two pieces but a single feature, be two separate features in an attribute table. I need it to be two separate features.
    – Nathan
    Dec 1 '15 at 15:08
  • It would actually be the Explode function, since it is a multi-part polygon under the Advanced Editor toolbar FYI.
    – Nathan
    Dec 1 '15 at 15:31
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With ArcGIS for Desktop Basic, you can use the Cut Polygons tool on the Editor toolbar to perform this task. You can cut multiple polygons this way, but the cut line is based on a sketch you draw manually.

Click the Cut Polygons tool on the Editor toolbar. Select the necessary drawing tools (line, tract, etc) and draw an appropriate line to split by. If you need to split based on another polyline or polygon, use snapping tools to help you cut.

One of the resulting polygons will retain the original OID (i believe the larger) and the other will be a new feature with a new OID. All resulting features will retain original attributes, which can be changed if necessary (e.g. to change parcel numbers, etc.).

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  • I do not see a 'cut polygons' tool at all within my editing bar. I was looking for that, and was pretty sure it existed, but don't see it. Is there a reason for this or a way I can add it?
    – Nathan
    Dec 1 '15 at 14:46
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    On the Editing toolbar, select the dropdown arrow on the far right, select "Customize..." When the Customize window opens, select the Commands tab. Here you can either search for the tool (on the top right) or select the "Editor" under categories (on the left), which will then allow you to select the tool on the right. Once you find it, drag and drop it on the Editor toolbar, or anywhere to your liking.
    – Barbarossa
    Dec 1 '15 at 14:51
  • Ok, when I go to cut polygon it gives me an error message when I finish sketch. It says it could not be completed because a polygon cut could not be classified as left or right of the cutting line. Do you know what this means or how I can fix this?
    – Nathan
    Dec 1 '15 at 14:53
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    If ArcMap cannot determine left or right, then the cutting line was not sufficient enough to cut the polygon. Ensure your cutting line crosses the entire polygon, past the boundary to be safe.
    – Barbarossa
    Dec 1 '15 at 14:56
  • I did that. Then it just gives me a tiny line as the new feature in the attribute table, and didn't even split my poly into two. I can't believe something so simple is this difficult.
    – Nathan
    Dec 1 '15 at 15:21

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