Structure of SIC Codes: Divisions, Major Groups, Industry Groups, and 4-Digit Industries (Plus Extended SIC)

Updated: 2026
Reviewed By: SICCODE.com Industry Classification Review Team
Data Lineage: About Our Data Team

The SIC system is a hierarchy that lets you tabulate establishment data at different levels: Division → Major Group (2-digit) → Industry Group (3-digit) → Industry (4-digit). “Extended SIC” (6–8 digits) are non-standard, vendor-defined subdivisions built on top of official 4-digit SIC industries.

Structure of the Standard Industrial Classification

The structure of the Standard Industrial Classification (SIC) makes it possible to tabulate, analyze, and publish establishment data at the level of industrial detail considered most appropriate—by Division, 2-digit Major Group, 3-digit Industry Group, or 4-digit Industry.

In practice, many datasets and agencies rely on the standardized 4-digit SIC industry as the anchor for comparability. Some organizations also use additional subdivisions within specific 4-digit industries for their own operational needs. Those subdivisions are commonly referred to as Extended SIC Codes Vendor-defined.

Governance note: Official U.S. SIC is standardized at the 4-digit level Official. “Extended SIC” (6–8 digits) are widely used in the private sector, but they are not an official government standard. If you use extended codes, document the taxonomy provider/source to preserve auditability.

How “9” Works in SIC (NEC / Not Elsewhere Classified)

The digit “9” appearing in the third- or fourth-digit position often designates residual categories for establishments not elsewhere classified (NEC). These categories may be less homogeneous than other groups, but they help preserve the consistency of the broader classification by providing a defined “catch-all” where an exact match is not available.

SIC Structure Table

US Govt. SIC Codes Official Extended SIC Codes Vendor-defined
Division Title Major Group
2-digit		 Industry Group
3-digit		 Industry
4-digit		 Total 6-digit 7-digit 8-digit
A
01-09		 Agriculture, Forestry, Fishing 5 23 58 86 245 662 525
B
10-14		 Mining 4 20 31 55 98 410 362
C
15-17		 Construction 3 14 26 43 522 780 410
D
20-39		 Manufacturing 20 140 459 619 2,709 10,930 9,571
E
40-49		 Transportation & Public Utilities 10 37 67 114 424 732 451
F
50-51		 Wholesale Trade 2 18 69 89 2,082 3,315 1,757
G
52-59		 Retail Trade 8 41 64 113 1,288 1,835 859
H
60-67		 Finance Insurance, Real Estate 7 30 53 90 298 576 378
I
70-79		 Services 16 71 150 237 2,703 4,269 2,260
J
91-99		 Public Administration 8 22 28 58 156 412 356
  Total 83 416 1,055 1,504 10,525* 23,921* 16,929*

*Note: Extended SIC Codes are continuously updated to reflect the current marketplace. Extended code definitions are vendor-defined and may vary by source.

How to Use This Structure in Practice

  • Broad reporting: Use Division or 2-digit Major Group when you need high-level rollups.
  • Industry comparison: Use 3-digit Industry Groups for mid-level segmentation across related activities.
  • Most common “official” anchor: Use 4-digit SIC industries for standardized classification and cross-dataset comparability.
  • Granular targeting: Use Extended SIC (6–8 digits) for private-sector segmentation, but record the provider/source taxonomy.

Rule of Thumb: When accuracy and comparability matter, anchor on the 4-digit SIC. Use extended codes for additional detail only when you can name and retain the source taxonomy.