Final answer:
The National Credit Union Administration (NCUA) is the federal agency responsible for supervising and regulating credit unions in the United States.
Step-by-step explanation:
The independent federal agency designed to monitor and regulate the country's credit unions is the National Credit Union Administration (NCUA). This agency supervises credit unions, which are nonprofit financial institutions owned and run by their members. The NCUA ensures that these credit unions maintain positive net worth and do not engage in excessively risky practices, providing oversight similar to how the Office of the Comptroller of the Currency regulates banks and savings and loan institutions under the U.S. Department of the Treasury.