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Problem: Shapefile polygons have negative areas or label incorrectly

Description

Shapefiles containing invalid geometries exhibit the following odd behavior:
 

• Incorrect area calculations containing negative values.
• Label placement is off in ArcMap.

Cause

These problems are the result of bad geometries, the most common of which are:

• Self intersecting features, such as lines and polygons.
• Incorrect ring ordering of polygons.

ArcInfo and ArcGIS cannot create these types of geometries. The most likely sources of the geometries are other programs writing the geometries into the shapefile.

Solution or Workaround

Run the Repair Geometry Geoprocessing tool: ArcToolbox > Data Management Tools > Features > Repair Geometry.