Questions about 1981 CSD Maps on DLI ftp site

Question

I've questions about the three versions of census subdivision digital boundary files available on the DLI ftp site in directory geography/1981/arcinfo - csd1981_dbf.zip, csd_sdr81.zip, and csd_sdr1981.zip (as listed on the Spatial Product Inventory found in geography/1981/document).

Having extracted them out to disk, I see that the ArcInfo interchange files have different dates (12/16/1998, 11/17/1998, and 9/16/1999 respectively).

When I load the files into ArcMap, however (after converting with ArcToolbox), I don't see any apparent differences.

Would someone with more map experience point out to me what I should be looking for and/or at to tell this? Is there one version of this file that should be considered authoritative? What are the different versions used for?

Answer

There are no differences in the files other than the names of some of the columns and the number of columns are different. Check the table for each of the files and you will see the difference.