Industry Classification and Definitions
Standard Industrial Classification (SIC)
[Reference] HF1042 .A55 1987 Catalog Record
Industrial classification system used to describe the structure of American industries. A hierarchical system, industries are organized into broad industry groups and then subdivided into smaller groups. Each industry carries a unique four-digit classification code ranging from 0100 to 9999. The SIC was replaced in 1997 with the North American Industrial Classification System but many sources still use the SIC.
North American Industry Classification System (NAICS)
[Reference] HF1042 .N67 2002 Catalog Record
Created by the Census Bureau in 1997, NAICS replaced the SIC. NAICS includes many newer industries in addition to being a uniform classification system for Canada, the U.S., and Mexico. Like the SIC, it is hierarchical and classifies each industry by broad group and then subdivides each into smaller, more specific classification. Each industry is assigned a unique number.