Currently, industries are defined according to the 2002 North American Industry Classification System (NAICS This system, which was established by the United States, Canada, and Mexico, provides a consistent framework for the collection, analysis, and dissemination of industrial statistics in the three North American countries The NAICS classifies economic units that have similar production processes in the same industry and the lines drawn between industries demarcate, to the extent practicable, differences in production processes.
GDP-by-industry estimates for 1947-1997 are also published for industries defined according to the 1987 Standard Industrial Classification system (SIC). The SIC classifies units according to their principal types of economic activity (products or services).