Does IPUMS documentation give detail on industry codes (i.e. how a given industry was defined in a given year)?

I am cross-tabbing industry and occupation variables for pharmaceutical and medicine manufacturing across three decades (1990-2010), using the IND1990 and OCC1990 codes. Wondering how to compare industry code 181 (used in the IND1990 variable, titled “Drugs”) with NAICS 3254 (“This industry group comprises establishments primarily engaged in one or more of the following: (1) manufacturing biological and medicinal products; (2) processing (i.e., grading, grinding, and milling) botanical drugs and herbs; (3) isolating active medicinal principals from botanical drugs and herbs; and (4) manufacturing pharmaceutical products intended for internal and external consumption in such forms as ampoules, tablets, capsules, vials, ointments, powders, solutions, and suspensions.”) But can’t seem to find a definition for Census Industry Code 181 in the IPUMS reference materials. Thank you!

Proposed Answer:

According to this crosswalk published by the Census Bureau, the 1990 code 181 (“Drugs”) directly corresponds to the 1997 NAICS code 3254 (and the 2000 code 219 " Pharmaceutical and medicine manufacturing"). The Census Bureau uses an Alphabetical Index to classify responses into standard industry codes, which is detailed in this publication. This publication also equates the 1990 Industry Code of 181 with the 1987 SIC code of 283, which you can look up using OSHA’s search tool for more detailed explanations of what qualifies for this code.

I hope this helps.