"Historical studies suggest that it takes 3.5% of a population engaged in sustained nonviolent resistance to topple brutal dictatorships."
Erica Chenoweth, co-author of Why Civil Resistance Works: The Strategic Logic of Nonviolent Conflict
https://www.theguardian.com/commentisfree/2017/feb/01/worried-american-democracy-study-activist-techniques
What percentage of the USA population participated in the 2018 Women’s March?
LA - 600,000
Chicago - 300,000
NY - 200,000
Atlanta - 60,000
SF - 50,000
Philadelphia - 50,000
Denver - 50,000
Oakland - more than 40,000
San Diego - 37,000
Seattle - “tens of thousands”
San Jose - 20,000
Raleigh, North Carolina - 17,000
Nashville - 15,000
Seneca Falls, NY - 12,000 to 15,000
Washington, D.C. - more than 10,000
Boston - 10,000
Olympia, WA - 8000
Omaha, Nebraska - 8,000
Fort Worth - 5000
Wynwood, FL - 2,500
Casper, Wyoming - 350
1,507,850 by my rough count of this representative sample.
The current USA population is about 326,000,000.
So at least 0.5% of the USA population came out for the 2018 Women’s March.