Trade associations & organizations can provide a wealth of information and statistics about an industry. Sometimes, this information is restricted to members-only. It's usually worth taking a look at their site to see what may be available for free.
If it is a members-only site, see if the association has been quoted in business trade publications, newspapers or magazines. You can do this by using their name as a search term in the databases listed under the "Business Articles" tab.
Try searching for the name of your industry + the word "organization" (or try "association"). This will usually bring up results for National or International groups. However, carefully judge the quality of the sites that you visit to make sure they are reputable organizations and data is gathered in a systematic and non-biased manner.
Industry reports are created by market research firms, investment analysts, and some government agencies. These are usually lengthy reports, focused on one industry, and updated regularly.
With the following databases, you can use the NAICS Code to create a list of competitors in an industry. Some allow you to narrow that list by other criteria, such as geography, sales, private/public ownership, etc.