You know. Things like NAFTA. Then take a look at TradeAgreements.gov:
"TradeAgreements.gov is an interagency effort by the United States Government to provide the public with the latest information on America's trade agreements. A joint effort between the Departments of Agriculture, Commerce, State, Treasury and the Office of the United States Trade Representative, this site will be regularly updated with news about existing agreements, as well as pending free trade agreements with Peru, Colombia, Panama and South Korea."