New from the Brennan Center for Justice at NYU Law, OpenSecrets, and the Wesleyan Media Project.

Key findings:

• Between January 1, 2023, and November 5, 2024, online political advertisers spent $1.35 billion to buy ads on Google and Meta.
• More than half of the spending ($729 million) was concentrated between September 1 and Election Day.
• Much of the late spending was driven by candidates and joint fundraising committees (40%), super PACs (26%), and national groups seeking to influence state ballot measure results (7%).
• Advertisers spent $61 million on state ballot campaigns, six times the figure ($10 million) for the period up to August 31, 2024. Most of the spending came from national donors rather than in-state residents. Abortion rights measures in Florida ($9 million) and Ohio ($3.7 million) were among the measuresattracting the heaviest spending.
• Democrat-aligned spending was almost three times as much as Republican-aligned spending.
• Some of the largest spenders were groups focused primarily on fundraising appeals, such as the Harris Victory Fund, which spent $179 million on online ads.

As the authors explain, transparency rules for online spending are weak compared to those that apply to political advertising on TV and radio. Digital ad platforms don’t have to publish political ad data, in contrast to broadcast media. Google (owner of YouTube) and Meta (owner of Facebook and Instagram) are unusual in that they make that information public and in a reasonably accessible format. Other ad platforms, including X (formerly Twitter), provide incomplete political ad data, if any.