History of SIC Codes: Origins, Revisions, 1987 Standard, and Extended SIC Today
SIC was created to standardize how agencies classify establishments so industrial statistics are comparable. The last U.S. Government revision occurred in 1987. Today, NAICS is the modern standard used for most current government statistical reporting, while SIC remains common in private-sector databases, vendor data products, and legacy research series where historical continuity matters. Many commercial datasets also use Extended SIC Codes for additional segmentation beyond the official 4-digit baseline.
Standard Industrial Classification (SIC) was introduced to make industry statistics comparable across agencies and time. While originally intended for statistical reporting, SIC codes also became embedded in long-running databases and commercial data environments. After NAICS was introduced, many organizations began storing both SIC and NAICS because they serve different operational needs across reporting, analytics, and continuity.
Important context: Official U.S. SIC is standardized at the 4-digit level. Extended SIC (6–8 digits) are vendor-defined subdivisions used in many commercial datasets. When you use extended codes, keep the 4-digit SIC as the anchor and document which taxonomy provider defined the extensions.
Beginning of SIC Codes
Industrial classification originated in a recommendation at an Interdepartmental Conference on Industrial Classification held in 1934. This recommendation, transmitted to the Central Statistical Board, suggested the establishment of a continuing committee to address the problems of industrial classification of statistical data.
In 1937, the Central Statistical Board established an Interdepartmental Committee on Industrial Classification to develop a plan for classifying statistical data by industries and to promote the general adoption of such classification as a standard for the Federal Government.
At its first meeting on June 22, 1937, a Technical Committee was established to prepare the proposed standard classification of industries. Standardization was a key objective because agencies collecting industrial data used their own classifications, making cross-agency comparison difficult and sometimes misleading.
The project was designed to classify “industry” broadly across all economic activity, including agriculture, mining, construction, manufacturing, wholesale and retail trade, finance/insurance/real estate, transportation/utilities, services, and public administration. The Technical Committee worked first on manufacturing industries. In June 1938 a list of industries was accepted, and expert subcommittees were later authorized for nonmanufacturing fields—leading to the creation of the Lists of Industries.
The List of Industries for manufacturing was first available in 1938, with the List of Industries for nonmanufacturing following in 1939. These Lists became the first Standard Industrial Classification (SIC) for the United States.
Early SIC Manual Volumes
Volume I, Manufacturing Industries
- Part 1 - List of Industries, 1938
- Part 2 - Description of Industries, 1940
- Part 3 - Alphabetic Index of Products, Establishments and Processes, 1939
- Part 4 - Alphabetic Index of Products, Establishments and Processes by Major Groups, 1939
Volume II, Nonmanufacturing Industries
- Part 1 - List of Industries, 1939
- Part 2 - Description of Industries, 1940
- Part 3 - Alphabetic Index of Products, Establishments, and Services, 1940
- Part 4 - Alphabetic Index of Products, Establishments and Services by Major Groups, 1940
SIC Code Revisions
After the 1939 SIC had been in use for a reasonable length of time, the Central Statistical Board transferred the project to the Bureau of the Budget. A review was conducted and appropriate revisions were made. Following the review, the first printed edition of Manufacturing Industries was published in 1941 and that of Nonmanufacturing Industries in 1942.
In 1945, a new edition of Volume I, Manufacturing Industries, of the SIC Manual was published in two parts:
- Part 1, Titles and Descriptions of Industries, November 1945
- Part 2, Alphabetic Index, December 1945
This reflected technological advances developed during World War II and changes recommended by users of the 1941 classification. A revision of Volume II, Nonmanufacturing Industries, was published in 1949, prepared with the same general principles and committee structure as earlier editions.
The revised SIC combining both manufacturing and nonmanufacturing industries into one book was published in July 1957. A review of the 1957 edition was completed in 1962 and amendments were incorporated in a supplement published in 1963. The 1967 revision resulted from data from the 1963 Economic Census and later reviews. Further revisions occurred in 1972 and 1977.
Why revisions mattered: Updates were driven by changes in how industries operated, how establishments reported activity, and how agencies needed to compare economic data consistently across time.
On February 22, 1984, the Office of Management and Budget (OMB) published a Federal Register notice of intent to revise the SIC for 1987. In response, businesses, trade associations, individuals, and federal/state/local agencies submitted proposals for over 1,100 individual changes. The last revision by the United States Government of the SIC was in 1987.
SIC and NAICS in Modern Data
Why SIC still appears
- Legacy continuity: many long-running datasets and time-series benchmarks were built on SIC fields.
- Vendor databases: many data providers still deliver SIC and/or extended SIC for segmentation and continuity.
- Enterprise systems: companies often retain SIC fields in CRM/ERP/data warehouses for historical alignment.
- Cross-dataset comparability: SIC can be useful when reconciling older sources that predate NAICS adoption.
Government context: What Government Agencies Still Use SIC Codes?
Why NAICS is the modern standard
- Current statistical reporting: NAICS is used for most modern government economic statistics.
- Official 6-digit structure: NAICS provides more official granularity than the 4-digit SIC baseline.
- Active revisions: NAICS updates incorporate changing industries and modern production structures.
- Modern data programs: many CRM and analytics teams standardize on NAICS for current-state definitions.
For the latest standard and definitions, see the 2022 NAICS Directory.
SIC Codes Today
In the official U.S. Government SIC system, there are 1,514 codes across the 2-digit, 3-digit, and 4-digit levels. The U.S. Government also specified that agencies could use additional subdivisions within specific four-digit industries while retaining comparability. Commercial datasets commonly refer to these subdivisions as Extended SIC Codes.
Extended SIC codes provide additional segmentation and can help represent narrower market niches in private-sector datasets. These extended taxonomies are widely used by researchers, analysts, developers, and marketing teams when they need finer segmentation than a single 4-digit SIC can provide, within the context of a specific provider’s definitions.
When the 4-digit SIC anchor matters most
- Legacy datasets and historical trend analysis
- Cross-dataset comparability when sources use different vendors
- Governed classification decisions that need a stable reference
When Extended SIC adds value
- Marketing segmentation and list building (provider-defined)
- Private databases that require finer industry detail
- Product/solution targeting where broad SIC groups are too coarse
Best practice: Store SIC and NAICS together when your workflows span historical continuity and modern standards-based reporting. NAICS is commonly used for current statistical and contracting contexts, while SIC supports legacy alignment and many private datasets. See SIC vs NAICS for a practical comparison.
System Selection Framework
| Feature | SIC | NAICS |
|---|---|---|
| Primary strength | Historical continuity & legacy alignment; common in vendor/provider databases | Modern economic reality & official 6-digit structure for current reporting |
| Granularity | Official baseline at 4 digits (extensions are vendor-defined) | Official structure through 6 digits |
| Revision cycle | Stable/static (last major government revision 1987) | Actively revised (e.g., 2017, 2022) to reflect evolving industries |
| Common best fit | Legacy database alignment, longitudinal research, certain commercial segmentation | Modern government reporting, emerging industries, current-state analytics standards |
Explore SIC Structure and Directories
- SIC Code Lookup / Directory
- Extended SIC Code Lookup / Directory
- Structure of SIC Codes
- What is a SIC Code?
- What is a NAICS Code?
- SIC vs NAICS Codes
- 2022 NAICS Directory
Bottom line: SIC remains a foundational classification for legacy comparability and many private-sector datasets, while NAICS is the modern standard for current government statistical reporting and official 6-digit definitions. Extended SIC taxonomies can add segmentation, but should be treated as vendor-defined layers anchored to the official 4-digit SIC standard.