A primary category containing information pertaining to passenger and freight transportation by rail, highway or water.  Including services such as stevedoring, backing, loading and unloading, pipe line transportation, warehousing (in transit).


Subject categories and sub-categories fully available for research are bolded. Closed categories and sub-categories have a simple phrase describing their contents.


                                 DESCRIPTION OF SECONDARY FILE CODES


File Code                         Description


TN                                  Transportation


TN001                             Highway Transportation


TN001-01                        Motor Pool


TN002                             Interurban Transportation


TN002-01                        Metropolitan D.C. Subway System


TN003                             Pipeline


TN004                             Railroad


TN005                             Water