Final answer:
The Federal Reserve Board, or 'the Fed', is responsible for enacting monetary policy in the United States, a role delegated to it by Congress through the Federal Reserve Act of 1913.
Step-by-step explanation:
The entity that enacts monetary policy in the United States is the Federal Reserve Board, commonly known as the Fed. This power was delegated to the Federal Reserve as part of the Federal Reserve Act of 1913, following the constitutional power granted to Congress to 'coin money' and 'regulate the value thereof'.
The Federal Reserve's operation includes managing interest rates and credit conditions, which in turn influences the level of economic activity. The primary tools used by the Fed to implement monetary policy include open market operations, changing reserve requirements, and modifying the discount rate. In practice, the Federal Reserve has enormous power over economic policy and can invoke changes with swift and potentially significant impacts on the economy.