This subject index presents the categories assigned in the 1940s to make it possible to browse the FSA/OWI photographs by what they depict. The Office of War Information used a decimal number classification scheme to organize the photos. This section of the list is arranged alphabetically by subject words taken from the heading cards in the FSA/OWI photographic print file, with a link that retrieves photos that are filed under the corresponding classification number. The categories and the words used to describe them are products of their era and have not been altered for this presentation.

• The same classification number may appear multiple times under synonyms, variant words, or inverted headings; for example: .576 is listed under both "Oil Wells" and "Petroleum."
• Not all numbers retrieve descriptions and images, either because the information has not yet been added to the description, or because the originating agency never applied the number to any photographs.
• For more information, view the introduction to this list.