Final answer:
The first regulatory agency in the U.S. was the Interstate Commerce Commission (ICC), set up to regulate railroads and ensure fair practices.
Step-by-step explanation:
The United States' first regulatory agency is the Interstate Commerce Commission (ICC), established by the Interstate Commerce Act of 1887. The ICC was created to regulate the railroads to ensure fair rates, to eliminate rate discrimination, and to regulate other aspects of common carriers, including pipeline and telegraph companies. While the ICC has been succeeded by other agencies and ultimately merged into the Surface Transportation Board, it laid the groundwork for future regulatory bodies, such as the Food and Drug Administration (FDA), and established the federal government's role in regulating industry.