Do you have a source or particular time frame in mind? Both methamphetamine and cocaine are schedule II drugs in the United States and fall under the same legislation.

Methamphetamine abuse is more common because it is cheaper and more common. It is also prescribed under the brand name Desoxyn, and it is more likely to make it on the news.

If you meant crack or freebase cocaine, then that is different. Crack is schedule II and falls under the legislation for cocaine, but the Drug Act of 1986 outlines stricter penalties for it. Crack is cheaper than pure cocaine and was more likely to be found in poor minority neighborhoods so it this law was used as a form of institutional racism. The law was amended with the fair sentencing act of 2010.