Sources

All spending figures are in nominal U.S. dollars (not inflation-adjusted).

Total cost of federal elections (CSV 03)

Total federal election spending by cycle (candidates + parties + outside groups), federal only, nominal dollars, from OpenSecrets, "Cost of Election." https://www.opensecrets.org/elections-overview/cost-of-election

• Verified figures: 2016 $6.5B; 2020 $15.1B (OpenSecrets revised, originally ~$14.4B); 2022 $8.9B (federal — the often-cited $16.7B for 2022 includes state races); 2024 $15.9B (preliminary/projected, via OpenSecrets / The Fulcrum, Oct 2024).
• Earlier cycles (2000–2014, 2018) are OpenSecrets' long-published nominal cost-of-election totals: 2000 $3.1B · 2002 $2.2B · 2004 $4.1B · 2006 $2.9B · 2008 $5.3B · 2010 $3.6B · 2012 $6.3B · 2014 $3.8B · 2018 $5.7B.

Independent expenditures & super PACs (CSV 01)

Totals are reported figures from the Federal Election Commission's end-of-cycle statistical summaries. Each row cites the specific summary. "Super PAC" is the FEC category Independent-Expenditure-Only Political Committees; "hybrid PAC" is Committees with Non-Contribution Accounts.

• FEC, Statistical Summary of 24-Month Campaign Activity, 2023–2024 cycle — independent expenditures $4.4 billion (super PACs $2.7B; hybrid PACs $1.4B); electioneering communications $11.3M.
• FEC, Statistical Summary, 2021–2022 cycle — IE $2.255B (super PACs $1.3B; hybrid $555M); EC $4.8M.
• FEC, Statistical Summary, 2019–2020 cycle — IE $3.1437B (super PACs $2.0B; hybrid $552.2M); EC $32.8M.
• FEC, Statistical Summary, 2017–2018 cycle — IE $1.301B (super PACs $820.5M; hybrid $72.9M); EC $15.3M.
• FEC, Statistical Summary, 2015–2016 cycle — IE $1.631B (super PACs $1.1B; hybrid $46.7M); EC $56.1M.
• FEC, Statistical Summary, 2013–2014 cycle — congressional IE $787.8M (super PACs $339.4M; hybrid $2.6M); EC $7.3M.
• FEC, Campaign activity of the 2011–2012 election cycle — IE more than $1.25B ($583.8M presidential + $666.7M House/Senate); EC $15.1M.

Source index: https://www.fec.gov/campaign-finance-data/campaign-finance-statistics/

Dark money (CSV 02)

Two methodologies, not directly comparable (see the report and data dictionary):

• 2010–2016 — OpenSecrets: spending by organizations that do not disclose their donors, as reported to the FEC. https://www.opensecrets.org/dark-money
• 2020 & 2024 — Brennan Center for Justice: Dark Money Hit a Record High of $1.9 Billion in 2024 Federal Races (2024), combining FEC-reported spending with undisclosed television advertising (Wesleyan Media Project) and digital ad sales. Reports dark money of ~$1B (2020) and $1.9B (2024), and at least $4.3B cumulatively since Citizens United. https://www.brennancenter.org/our-work/research-reports/dark-money-hit-record-high-19-billion-2024-federal-races

Background

• Citizens United v. FEC, 558 U.S. 310 (2010).
• SpeechNow.org v. FEC, 599 F.3d 686 (D.C. Cir. 2010) — the decision that enabled super PACs.
• Brennan Center, Citizens United, Explained. https://www.brennancenter.org/our-work/research-reports/citizens-united-explained