topic &amp;quot;Unknown Coordinate System&amp;quot; error in ArcGIS Explorer Desktop Questions https://community.esri.com/t5/arcgis-explorer-desktop-questions/amp-quot-unknown-coordinate-system-amp-quot-error/m-p/242137#M1518 <HTML><HEAD></HEAD><BODY><SPAN>I get an error Failed to add shapefile ...(Unknown Coordinate System) when attemptin to add some of teh many files supplied to me by Statistics South Africa.&nbsp; They assure me all files in the Census 2001 and Census 2011 package have been made in the same way and they are able to load them all.</SPAN><BR /><BR /><SPAN>Where could the problem be?</SPAN></BODY></HTML> Sun, 16 Feb 2014 13:53:16 GMT JoeBoniaszczuk 2014-02-16T13:53:16Z &quot;Unknown Coordinate System&quot; error https://community.esri.com/t5/arcgis-explorer-desktop-questions/amp-quot-unknown-coordinate-system-amp-quot-error/m-p/242137#M1518 <HTML><HEAD></HEAD><BODY><SPAN>I get an error Failed to add shapefile ...(Unknown Coordinate System) when attemptin to add some of teh many files supplied to me by Statistics South Africa.&nbsp; They assure me all files in the Census 2001 and Census 2011 package have been made in the same way and they are able to load them all.</SPAN><BR /><BR /><SPAN>Where could the problem be?</SPAN></BODY></HTML> Sun, 16 Feb 2014 13:53:16 GMT https://community.esri.com/t5/arcgis-explorer-desktop-questions/amp-quot-unknown-coordinate-system-amp-quot-error/m-p/242137#M1518 JoeBoniaszczuk 2014-02-16T13:53:16Z Re: "Unknown Coordinate System" error https://community.esri.com/t5/arcgis-explorer-desktop-questions/amp-quot-unknown-coordinate-system-amp-quot-error/m-p/242138#M1519 <HTML><HEAD></HEAD><BODY><SPAN>The files lack a *.prj file which defines what the coordinate system.&nbsp; You need to use the Define Projection tool to define them.&nbsp; The source site must have some information on this</SPAN></BODY></HTML> Sun, 16 Feb 2014 14:19:40 GMT https://community.esri.com/t5/arcgis-explorer-desktop-questions/amp-quot-unknown-coordinate-system-amp-quot-error/m-p/242138#M1519 DanPatterson_Retired 2014-02-16T14:19:40Z