Publication rules apply primarily to publicly held corporations. AFAIK, this is not a question of size, employee number, etc., but simply a question of whether the shares of the company are publicly traded.
In addition, certain companies also fall under a number of different regulations, such as utilities regulations (power companies, phone companies, etc.), which can also affect publication duties.
Most critical for your question, however, is the fact that in the U.S., you would have to check the specific state laws of whatever state you are in as well as federal law. At least for federal law, this may be a good start:http://www.sec.gov/
(it's the Securities Exchange Commission).
Hope that helps a little.