The world of US political adverts explained in 60 seconds
The 2014 mid-term election in the US is projected to break records in the money spent by candidates and political groups.
A large portion of the money will go to adverts which reach the eyes and ears of 80% of Americans.
But how effective are these political adverts and just how much do they cost?
Data compiled by the Pew Research Center, external presents a clear picture of the political battles over the airwaves.
Produced by the BBC's David Botti