A more thorough explanation:

The Hepburn Act was a law passed by the United States government in 1906. It changed the rules for how companies that transport goods and people across state lines, called "common carriers," could operate.

The Hepburn Act did four main things:

1. It gave the Interstate Commerce Commission more power to regulate pipelines.
2. It made it illegal for common carriers to give free rides to anyone except their own employees.
3. It made it illegal for common carriers to transport any products that they had a financial interest in, except for timber.
4. It required common carriers to work together to set prices and keep track of their finances in a consistent way.

For example, imagine that a railroad company also owned a coal mine. Before the Hepburn Act, that company could transport its own coal on its own trains without any oversight. But after the Hepburn Act, the company would have to use a different carrier to transport its coal, or it would have to follow strict rules to make sure it wasn't giving itself an unfair advantage.

The Hepburn Act was an important step in regulating the power of big businesses in the early 1900s. It helped to make sure that common carriers were treating everyone fairly and not using their power to hurt smaller companies or individuals.