Final answer:
The Federal Reserve Act of 1913 created the central banking system in the United States known as the Federal Reserve, responsible for regulating monetary policy.
Step-by-step explanation:
The legislative act that created a central banking system responsible for the regulation of monetary policy in the United States is the Federal Reserve Act of 1913. This act established the modern central banking system known as the Federal Reserve, or the Fed. The Fed acts as a central bank for the government and has the authority to set monetary policies that affect the economy, such as controlling the federal funds rate, which is the interest rate commercial banks pay to borrow money.