Super PACs now dominate

Super PACs — formally "independent-expenditure-only political committees" — did not exist before 2010. In 2012, their first presidential cycle, they reported $606.8 million in independent expenditures; by 2016 that had grown to $1.1 billion of the $1.6 billion total, and by 2024 to $2.7 billion, roughly six in every ten outside dollars. Add "hybrid" PACs (which keep a separate unlimited account) and the two vehicles created in Citizens United's wake made up nearly $4.1 billion of the $4.4 billion spent in 2024.