Wikipedia maintains a list: https://en.wikipedia.org/wiki/List_of_protests_and_demonstrations_in_the_United_States_by_size

The hands off protest of April 5th took the 5th position, with between 3 and 5 million participants. Will another protest in the US, before July 7th, unambiguously earn a position in the top 10? (This would require at least 1 million participants in a single day.)

(To be clear: vandalism to Wikipedia will not count. The protest must be independently and reputably reported with sufficient participation.)

• Update 2025-04-08 (PST) (AI summary of creator comment): Update from creator

  • Organizer Claim Requirement: Organizers must claim more than 1 million participants in a single day.

  • Use of Independent Sources: Resolution will prioritize independent media estimates. If these are unavailable, the largest single location independent estimate will be used.

  • Fermi Estimate Fallback: A Fermi estimate based on a half dozen local events with independent reporting will be applied. If this estimate is less than 2 million, the market will resolve as NO.

  • Role of Wikipedia: Wikipedia is used solely as the source for the top 10 threshold and is not the basis for the resolution criteria.