NAICS and SIC: Determine the code for your industry via the Census Bureau directory (or IBISWorld database; access link in list below) and review the appropriate Economic Census and other reports.
Look for links from nonprofit organization web sites and other areas. Use Google Advanced Search to identify local organizations, limiting to nonprofit and government domains. For example, search: massachusetts homeless site:.org;.gov
The Plunkett Research database also includes lists of trade associations by industry (access link in list below).
