Here is a Sway presentation about money in American politics. Be patient – it loads slowly. Hit fullscreen!
Microsoft Office Sway is pretty cool, you should check it out.
In 2010, the Supreme Court ruled that limiting the amount of money that corporations can spend on donating money to politicians is unconstitutional, because is the same as putting limits on free speech. This ruling is known as «Citizens United. Here is a video that explains it: