The Worker Adjustment and Retraining Notification Act (i.e., "The WARN Act") requires employers in the U.S. to provide written notice of plant closings to the "state dislocated worker unit designed or created under the Job Training Partnership Act." The names, addresses and phone numbers of the appropriate agencies are listed in West's Employment Coordinator. The Employment Coordinator also provides information on preparing the notices.
You can find the appropriate agency, and get other information, by calling the relevant Rapid Response Coordinator (formerly the "State Dislocated Worker Unit Coordinator"). Contact information for the Coordinator for each state is posted by the Department of Labor.
Research Tip: The WARN Act -- as well as state plant-closing laws -- are discussed in the Corporate Counsel's Guide to Reductions in Force and Reductions in Force in Employment Law (BNA Books). The WARN Act is also discussed in the "Individual Employment Rights Manual" volume/section of BNA's Labor Relations Reporter.
State plant closing laws are included in the individual state law chapters at the end of the "Individual Employment Rights Manual" print volume of BNA's Labor Relations Reporter (you can look them up in the index under "Plant Closing"). They are discussed in the CCH State Employment Law Library on Intelliconnect under the heading "Plant Closing Laws."
BNA Tax Management Portfolio #398, Reductions in Force discusses the tax implications of large layoffs.