Dark Money by the Numbers: Spending Totals and Trends

Spending by politically active nonprofits that are not required to disclose their donors — commonly called "dark money" — has grown from a marginal factor in federal elections to a nine-figure fixture in competitive cycles. This page covers how those totals are measured, what structural mechanisms produce the figures, where dark money flows in practice, and how analysts distinguish true dark money from adjacent spending categories. The numbers documented here draw on Federal Election Commission filings, IRS records, and nonprofit research tracked through organizations such as OpenSecrets and the Brennan Center for Justice.

Definition and scope

"Dark money" refers to political spending by organizations that are legally permitted to engage in election-related activity without publicly disclosing their donors. The primary vehicles are 501(c)(4) social welfare nonprofits and 501(c)(6) trade associations, both of which can spend on political communications and issue advocacy while keeping contributor lists confidential under IRS rules.

OpenSecrets, which maintains the most comprehensive public database of this spending, has tracked dark money totals since the 2010 election cycle — the first federal cycle following the Supreme Court's Citizens United v. Federal Election Commission decision. In the 2010 cycle, outside spending by nonprofits that did not disclose donors reached approximately $135 million, according to OpenSecrets dark money tracking data. By the 2020 presidential cycle, that figure had climbed to over $1 billion for the first time in a single cycle — a figure the Brennan Center for Justice has cited in its campaign finance reform analyses.

The scope extends beyond federal races. Dark money flows into state legislative contests, gubernatorial campaigns, judicial elections, and ballot measure campaigns, each governed by a distinct patchwork of state disclosure laws. The OpenSecrets dark money data portal aggregates federal-level figures; state-level totals are tracked with varying degrees of completeness by individual state ethics and election commissions.

How it works

The spending totals documented above result from a specific structural chain that keeps donor identity off public records.

1. Donor contribution: An individual, corporation, or other entity contributes to a 501(c)(4) nonprofit. No public disclosure is required at the federal level for this transaction, provided the organization itself does not register as a political committee with the FEC.
2. Organizational spending: The nonprofit spends funds on "issue ads," electioneering communications, or independent expenditures. If spending qualifies as an independent expenditure — explicitly advocating for or against a named candidate — the nonprofit must file with the FEC disclosing the expenditure amount and the organization's name, but not the underlying donors.
3. Pass-through transfers: Funds often move through pass-through nonprofits before reaching the entity that actually makes the public-facing expenditure, adding additional layers that obscure original sourcing.
4. Super PAC coordination: 501(c)(4)s may contribute unlimited funds to Super PACs, which do disclose donors — but if the listed donor is itself a nonprofit with undisclosed contributors, the disclosure is incomplete. OpenSecrets designates such Super PAC receipts as "dark money" in its accounting methodology.

The FEC's electioneering communication rules, codified at 11 C.F.R. § 104.20, require disclosure of expenditures exceeding $10,000 in an election period — but only the spending entity, not its donors.

This mechanism is examined in depth at 501(c)(4) organizations and dark money and the FEC disclosure rules for dark money reference pages.

Common scenarios

Dark money spending concentrates in predictable contexts:

• Senate battleground races: Competitive Senate contests in states such as Arizona, Georgia, and Nevada have drawn the largest single-race concentrations of nonprofit political spending in recent cycles.
• Presidential election cycles: The 2016 and 2020 presidential cycles each produced record dark money totals at the time of their occurrence, with the 2020 cycle crossing the $1 billion threshold noted above.
• Supreme Court confirmation battles: External nonprofit spending around confirmation hearings — most prominently the campaigns surrounding the 2017 Gorsuch and 2018 Kavanaugh nominations — has been documented in dark money in Supreme Court confirmations research by the Brennan Center for Justice.
• Ballot measures: Initiatives addressing tax policy, environmental regulation, and healthcare financing attract organized nonprofit spending. Dark money in ballot measures operates under state-level rules that differ substantially from federal disclosure requirements.

The contrast between these scenarios and standard disclosed campaign finance is structural: a Super PAC's donor list is publicly searchable through the FEC's electronic disclosure database within 48 hours of a contribution in the pre-election period, while a 501(c)(4) donor list is never required to enter any public record. The broader dark money vs. Super PACs comparison clarifies where these two categories diverge operationally.

Decision boundaries

Analysts and journalists tracking dark money spending must apply consistent classification rules to avoid overstating or understating totals. The homepage for this reference resource explains the definitional framework in detail, but several boundary questions recur in practice:

What counts as dark money vs. disclosed outside spending? OpenSecrets counts spending as dark money only when the original source donors remain undisclosed. If a nonprofit discloses its donors in state filings, that spending may be reclassified.

Does issue advocacy count? Spending on ads that do not explicitly call for a vote for or against a candidate — "issue advocacy" — is not reportable as an independent expenditure under FEC rules. Whether to count it as political dark money is a methodological choice: OpenSecrets and the Brennan Center for Justice include electioneering communications meeting statutory thresholds; narrower definitions exclude them.

Party-by-party distribution: OpenSecrets data shows that dark money has not been evenly distributed between parties across all cycles. Conservative-aligned nonprofits dominated the post-Citizens United cycles from 2010 through approximately 2014. Liberal-aligned groups produced greater totals in the 2020 cycle, according to OpenSecrets cycle-level breakdowns. The dark money donor networks page documents the major organizational clusters on each side.

Total vs. cycle-adjusted comparisons: Raw dollar totals are not directly comparable across cycles without adjusting for overall outside spending growth. As a share of total outside spending, dark money's proportion has fluctuated rather than risen monotonically, because Super PAC spending has grown alongside nonprofit spending.