Change in Industry Classification Systems The year 2000 data was
the last from the Quarterly Census of Employment and Wages
(ES-202) program using the 1987 Standard Industrial
Classification (SIC) system. With the release of data for 2001,
the program switched to the 2002 version of the North American
Industry Classification System (NAICS) as the basis for the
assignment and tabulation of economic data by industry. NAICS is
the product of a cooperative effort on the part of the
statistical agencies of the United States, Canada, and Mexico.
Due to differences in NAICS and SIC structures, data for 2001 is
not comparable to the SIC-based data for earlier years. NAICS
uses a production-oriented approach to categorize economic
units. Units with similar production processes are classified in
the same industry. NAICS focuses on how products and services
are created, as opposed to the SIC focus on what is produced.
This approach yields significantly different industry groupings
than those produced by the SIC approach