The 2018 midterm elections were the most expensive in history, and much of the money that financed them was undisclosed, or “dark.” There has always been big money in elections, of course, and some of it has always been dark. In the first Gilded Age, all campaign contributions were made in secret.
Hillary Clinton says she wants to get big money out of elections, and one of the ways she wants to do it is to curb the influence of big donors by mobilizing lots of small ones. This reform idea has become very popular recently, thanks to the concern about super PACs and billionaires that has been growing since Citizens United. But the idea is an old one. The first serious small-donor programs began more than 100 years ago, and they have been working more or less continually ever since.