From the U.S. Census Bureau, industry statistics specific to a particular county and industry. The statistics list number of establishments within a particular field by payroll and number of employees. Statistics are available for each of the past years dating back to 1998.
The predecessor to the NAICS system, SIC codes are still used alongside NAICS in many directories and data sources. Search for SIC codes by keyword or number, or click on SIC Manual to browse the classification hierarchy.
A global retail trade association, the NRF offers a website with research reports and news on the retail industry. Click the "Industry Information" tab to view News articles and research reports on the state of retailing online, retail industry indicators, and top retailers.