USA.gov is the federal government portal. Websites for all agencies in all branches of the federal government can be accessed from here by the name of the agency or through a subject search.
The United States Trade Representative is responsible for directing all trade negotiations of and formulating trade policy for the United States.
Congressional Publications indexes CIS/Index to Publications of the U.S. Congress since 1970; bills, laws and legislation; as well as information about members of Congress. Hearing of the international relations and business committees can be found, with more recent materials in full text. It will also include appointment hearings of individuals selected by the President to serve in roles as ambassadors and other diplomats.
GPO Catalog of Government Publications indexes government publications printed, posted, and/or distributed by the U.S. Government Publishing Office.