There was the Sherman Act, the first of the anti-trust laws, which disallowed monopolies, and price fixing. to ensure the consumer a fair price by preventing one company from controlling an entire market, thereby insuring a particular product would need to be priced competitively.
There was also the Interstate Commerce Act which prohibited the railroads from both price gouging and price discrimination, ie. charging more for smaller loads and shorter distances, which greatly affected small business like farmers, who couldn't afford to pay more for less, and big businesses were paying less for more. Sound familiar? This Act forced railroads to have one fair rate applying to everyone, and it must be posted for all to see.