Just one day after millions flooded the streets for the “No Kings” Day of Defiance, the protest is already being called one of the largest in U.S. history. But where does it rank? From Earth Day to Black Lives Matter, here’s how America’s biggest mobilizations stack up.
Below is a chronological tour of the largest protest mobilisations ever recorded on U.S. soil. Crowd figures are always estimates, but each of these events is backed by reputable crowd‑science, academic or contemporary media documentation.
Earth Day (1970)
On April 22, 1970 some 20 million people—about 10 percent of the U.S. population at the time—took part in teach‑ins, clean‑ups and rallies in more than 10,000 towns and campuses. The outpouring helped spur creation of the Environmental Protection Agency and the modern environmental movement.
Vietnam War Moratorium (October 1969)
The “Moratorium to End the War in Vietnam” synchronised local vigils, walk‑outs and marches across the country. Historians put nationwide turnout near 2 million, with about 200,000 candle‑carrying marchers in Washington, D.C. alone—at that point the biggest political action in U.S. history.
Nuclear‑Disarmament Rally, New York (June 1982)
Peace groups filled Central Park and mid‑Manhattan with 750,000 – 1 million demonstrators demanding a freeze on the arms race—still the largest single nuclear‑protest ever held in the United States.
March on Washington for Lesbian, Gay & Bi Equal Rights (April 1993)
Organisers and D.C. Police agreed the LGBTQ rights march drew 800,000 – 1 million people, eclipsing earlier pride mobilisations and placing equality issues onto the national legislative agenda years before marriage‑equality became law.
March for Women’s Lives (April 2004)
Led by a seven‑organization coalition, this reproductive‑rights rally attracted roughly 1.15 million people to the National Mall—then a record for a women‑led demonstration in the capital.
“A Day Without Immigrants” / Great American Boycott (May 2006)
Capping eight weeks of immigration‑reform marches, May Day actions shut down schools and businesses in more than 100 cities. Scholars and contemporaneous media place national participation in the 1.5 – 2 million range, including at least half‑a‑million in Los Angeles alone.
Women’s March (January 2017)
Sparked by Donald Trump’s inauguration, sister marches in all 50 states pulled 3.3 – 4.6 million participants; crowd‑science specialists counted about 500,000 in Washington, D.C., making it the largest single‑day protest up to that point.
March for Our Lives (March 2018)
Led by Parkland, FL students, more than 1.2 – 2 million people protested gun violence at 450‑plus U.S. sites, with 200k‑800k on Pennsylvania Avenue in D.C. The action fast‑tracked “red‑flag” gun laws in a dozen states.
George Floyd / Black Lives Matter Protests (Summer 2020)
Polling and event‑count data indicate 15 – 26 million Americans joined at least one racial‑justice demonstration during the first three months after Floyd’s murder—by far the largest protest wave in U.S. history. A single‑day high of about 500,000 was logged on 6 June 2020.
“No Kings” Day of Defiance (June 14, 2025)
Counter‑programming President Trump’s Flag‑Day military parade, the decentralised “No Kings” mobilisation staged 2,000‑plus local actions. Early crowd‑science estimates point to 4 – 6 million participants—enough to rival Earth Day 1970 for second place if the upper range holds.
Why these numbers matter
Mass protests often precede major legislative or cultural shifts—whether the creation of the EPA, passage of civil‑rights acts, a near‑halt to nuclear‑arms expansion or today’s debates over policing and democratic backsliding. Counting participants helps quantify public sentiment and, in some cases, legitimizes movements in the eyes of policymakers. Even in an era of digital activism, the sheer physical scale of these gatherings shows how Americans still “vote with their feet” when an issue hits home.
