SAN FRANCISCO (Diya TV) — Crowd estimates from Women’s Marches on Saturday are still trickling in, but some of the nation’s political scientists are saying they think we might have just witnessed the largest day of demonstrations in the history of the country.

According to data collected by Erica Chenoweth at the University of Denver and Jeremy Pressman at the University of Connecticut, marches held in more than 500 US cities were attended by at least 3.3 million people.

“Even using a conservative estimate, it was the single largest day for a demonstration in the US,” Chenoweth, an expert on political protests and civil resistance, told Vox.

Nearly every state in the union hosted a Women’s March on Saturday. The events ranged from small gatherings in small town squares, to groups of more than 500,000 flooding the streets of cities such as San Francisco, Chicago and Washington D.C. Pressman said he got his initial attendance figures from tracking numbers from local organizers, local media outlets and citizens who emailed or tweeted links with reports from early Saturday morning.

However, roughly 200 marches that took place across the country are still yet to release their attendance numbers, meaning researchers are still collecting a large portion of their data.

The turnout of marches outside of the U.S. was strong, too. Chenoweth and Pressman have recorded over 100 international Women’s Marches with an estimated attendance of more than 260,000.

But Chenoweth isn’t so sure the label of the largest turnout in U.S. history is absolute. For instance, she said, it’s possible that protests in cities around the US against the Iraq war in 2003 may have drawn as many people or more relative to the population at that time. The official count as of Saturday afternoon was 673 women’s marches in total — across all seven continents and in every corner of the globe.

See a slideshow of images from Saturday’s marches, and be sure to check out a complete gallery here.

Photos courtesy of News.Mic