As my history teacher always said it's always about the railroad XD So the answer to your question will be that the interstate commerce Act put regulations on the railroad.
The Interstate Commerce Act of 1877 was the first federal law that had as main purpose to insert regulations on the private industry, mainly the railroad industry and other transportation modes, as well as their monopolistic practices. It required railroad companies to establish fair prices to the consumers, to publish railroad rates, and banned the discrimination against small markets. The Interstate Commerce Act created the federal agency named Interstate Commerce Commission to monitor the railroad industry.
