From ProPublica:
Every local broadcast station has a repository of documents about political advertising that you have a legal right to see but can do so only by going to the station and asking to see “the public file.”
These paper files contain detailed data on all political ads that run on the channel, such as when they aired, who bought the time and how much they paid. It’s a transparency gold mine, allowing the public to see how campaigns and outside groups are influencing elections.
But TV executives have been fighting a Federal Communications Commission proposal to make the data accessible online. Since TV stations won’t put it online themselves, we decided to do it ourselves — and we want your help.