Mergent's global databases were used to identify publicly held U.S. manufacturing firms meeting IndustryWeek's criteria. This process was supplemented by additional research. Erik L. Fine, a Charlotte-based information consultant, assisted with the data collection.
The cutoff for inclusion on the 2003 IW U.S. 500 list was $872 million in annual revenues. The manufacturing companies in the IW U.S. 500 included: companies with a majority of their business in a manufacturing industry; companies that generated less than 50% of revenues from manufacturing, but more revenue from manufacturing than the lowest-revenue-producing companies on this year's list; computer software companies whose primary business is the manufacture of software products; oil and gas companies that derive at least 50% of their revenues from the refining of oil and gas products; and companies that derive at least 50% of their revenues from the manufacture of mined materials.
Mergent collected the financial data elements directly from financial reports distributed by the corporations. To more accurately reflect the companies' core business, only revenue numbers from continuing operations were used. An "NA" appears where data were not available.