Somewhere between 3.3 million and 4.6 million marchers made their presence known across the United States, yet no arrests were reported at the largest protests across the nation in Los Angeles, Washington D.C., New York, Chicago or Seattle.
That's according to political scientists from the Universities of Connecticut and Denver, who are compiling a mammoth spreadsheet listing march turnouts from the roughly half a million that demonstrated in Washington to the single protester who picketed Show Low, Arizona.
The largest single demo was in Los Angeles, where as many as 750,000 women thronged the streets. Meanwhile, sister protests across the globe attracted nearly 300,000 more attendees.
100,000 of those were in London, and there were marches in solidarity from Iraq to Antarctica.
Here's how the Women's March compares to some of history's largest protests (some in one city, some in thousands: some in Washington, some worldwide: some peaceful, some not):
Estimating crowd size is always difficult: where several different figures are available, the chart above takes an average.
The US National Park Service used to release estimates for US demos, but stopped doing so after Louis Farrakhan's 'Million Man March' in 1995, intended to unite the African-American community.
Their released figure of 400,000 was far lower than Farrakhan and other organisers had hoped for, and lower than the eventual total of around 837,000 arrived at by independent researchers. It was seen as an attempt to censor the impact of the march, and lead to a bitter row which overshadowed the demo itself.
Iraq War protests in 2003 hold the record for the largest demonstration both in a single city and across the globe: 3,000,000 are said to have marched in Rome, which has also been a flashpoint for labour demonstrations on a similar scale.
Organisers of an anti-corruption movement in India in 2012, meanwhile, claimed over 100,000,000 workers were involved in some capacity.
The Women's March does seem to have been the largest day of protest in US history, though other individual marches have exceeded the tally from Los Angeles or Washington, and in proportion to the country's population then some historic demos may have attracted a larger turnout.
But it's also remarkable for its peaceful nature. All these other major demos have, unsurprisingly, seen arrests. At a 1971 May Day action in Washington to protest the Vietnam War, protesters stopping traffic were subjected to the largest mass arrest in US history, as some 10,000 people were held by the National Guard.
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