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
TN001 Highway Transportation
TN001-01 Motor Pool
TN002 Interurban Transportation
TN002-01 Metropolitan D.C. Subway System