The FCC has announced new penalties against illegal radio transmitters. Financial penalties have been significantly increased from previous levels, of up to $100k per day..
These regulations only affect transmissions in the normal AM and FM radio broadcast bands. They have no effect against illegal transmitters or jammers operating in Wi-Fi or other frequency bands.
Traditionally called Pirate, Clandestine, or Free radio, they are often used by individuals and groups with ideas contrary to the wishes of the government. More common in large cites on the US east coast, they can be heard literally across the United States. Pirate stations were once common in Florida, produced by Cuban refugees with content aimed at their fellow citizens under the boot of the communist government of Fidel Castro.
See the following link for an official summary , which also contains an additional link to the full text of the new regulations.