The General Accounting Office is the audit, evaluation, and investigative arm of United States Congress. The GAO exists to support the Congress in meeting its Constitutional responsibilities and to help improve the performance and ensure the accountability of the federal government for the American people.
The GAO, a United States government electronic data provider, examines the use of public funds, evaluates federal programs and activities, and provides analyses, options, recommendations, and other assistance to help the Congress make effective oversight, policy, and funding decisions. In this context, GAO works to continuously improve the economy, efficiency, and effectiveness of the federal government through financial audits, program reviews and evaluations, analyses, legal opinions, investigations, and other services. The GAO's activities are designed to ensure the executive branch's accountability to the Congress under the Constitution and the government's accountability to the American people. The GAO is dedicated to good government through its commitment to the core values of accountability, integrity, and reliability.
Most reports come from requests from members of Congress, and so reflect conerns of current political import, but many reports are issued periodically and take a long view of US agencies' operations. Examples of these are the annual Performance and Accountability Series and High Risk Update.
Source: http://www.gao.gov