The Information Lab‘s Craig Bloodworth uploaded a fantastic tool to the free Alteryx Analytic Gallery that will convert any ZIP file containing ArcGIS SHP file information into Tableau polygons, and export that in either CSV or TDE.

All you need to do is sign up with Alteryx for free and then have a ZIP file to upload. For those new to all this, SHP or Shapefiles actually are composed of several files, so they are distributed in ZIP format to hold them all together.

https://gallery.alteryx.com/#!app/Tableau-Shapefile-to-Polygon-Converter/5296f89120aaf905b8e7fb48

These are the same techniques used by the folks over at http://tableaumapping.bi/ to build their shape sets, so you might find a useful one already converted over there.