My data: http://water.usgs.gov/GIS/dsdl/aquifrp025.tar.gz (USGS circa 2003 data on aquifers in the contiguous U.S.) Program: ArcGIS 10.1

The shapefile has no coordinate system or spatial reference. The metadata specifies NAD 1983 and in decimal degrees. My goal is to render this in such a way as to obtain 'normal' area/length/etc. values in meters for the purposes of calculating overlays with other spatial data. I cannot project the data because it has no coordinate system (error: no input coordinate system specified; paraphrasing)...batch/define doesn't work correctly either (the former same error, the latter (technically for use with rasters?) defines the projection, but reprojecting using the project tool doesn't do anything substantive (i.e. areas for huge swaths of the U.S. "46.1" etc. etc.).

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    Can you edit your question to include this duplicate post? – Paul Jul 25 '14 at 22:36
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    Your third paragraph directly contradicts itself: NAD 83 in decimal degrees is a perfectly fine spatial reference and is sufficient information for projecting the data. What specifically is the obstacle that you face in projecting them, then? – whuber Jul 25 '14 at 22:39
  • Sure! I hope URL's ok first time/longtime here-gis.stackexchange.com/questions/108410/… – user35039 Jul 25 '14 at 22:40
  • The metadata specifies that's what it should be projected with; the shapefile has no spatial reference data when it's opened in arcGIS. – user35039 Jul 25 '14 at 22:41
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    Welcome (back) to GIS SE! Rather than add to a trail of comments, the recommended way to provide clarifications requested by commenters is to use the edit button beneath your question to revise it. – PolyGeo Jul 25 '14 at 23:34

First, use Define Projection (from the Data Management / Projections and Transformations toolbox). The metadata specifies NAD 83 in decimal degrees, so, GCS_North_American_1983. This gives the shapefile some spatial reference data.

After that, you can use Project to turn it into whatever projected coordinate system you want.

  • Awesome. Stupid, stupid oversight on my part. My sincere and everlasting appreciation to you. – user35039 Jul 25 '14 at 23:39

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