A short list of eleven industry sectors are covered by Boogar Associates' Associations: Directory.
The American Society of Association Executives maintains a directory of trade associations, membership societies, and other not-for-profit associations at its Gateway to Associations, which is searchable by keyword (but not by category).
Many national trade associations are also listed at:
Other state-wide trade associations are included on these sites:
Many trade associations collect and publish information on their industry sectors. Start with the Encyclopedia of Business Information Sources (CAMDEN, CARR REF HE 5351 .E52; DANA Reference desk}, a guide to handbooks, statistical sources, directories, periodicals, and trade associations for specific industries.
The Encyclopedia of Associations (ALEXANDER REF HS 17 .G3323; DANA, DOUGLASS, CARR Reference desk} is more extensive in its coverage, but you have to start with an organization's name.
National Trade and Professional Associations of the United States (ALEXANDER, DANA, CARR, LSM REF HD 2425 .D53; CAMDEN Reference desk}