Some useful places to begin:
Government Accountability Office (GAO) : Known as "the investigative arm of Congress" and "the congressional watchdog." GAO supports the Congress in meeting its constitutional responsibilities and helps improve the performance and accountability of the federal government for the benefit of the American people.
For more see the Government Information portal at Columbia.
Department of State: The primary source of foreign affairs information for the U.S. Government and is responsible for implementing the President's foreign policies.
Don't forget that the State Department has had many versions of their website that can be accessed at their web-archive.