Corporate credit unions are united on a cooperative basis in the Central Credit Union (US Central Credit Union). National Credit Union Administration (NCUA) - an independent federal agency, based in Washington (State of Columbia), established by the U.S. Congress to oversee the federal credit union system. Over 30% of the assets of credit unions are investments in government securities, certificates of deposit of banks and savings loan associations, as well as in the parent credit unions, and other risk-free investments. Historically, credit unions have grown from the experience of credit cooperatives, but they took the experience of organizations of mutual aid of citizens by moving methods of social self-protection from labor and toward consumption.