What is the 3.5% protest rule and what does it mean for the US?

As the anti-Trump resistance has grown, so has talk of 3.5%, a figure which stems from research on previous movements

The number is frequently cited in leftwing circles, serving as a rallying cry for people who oppose Donald Trump: if 3.5% of a population protests against a regime, the regime will fail.

Left-leaning content creators, activists and media have boosted the 3.5% rule as the anti-Trump resistance has grown. A Pod Save America episode in June was headlined The 3.5% Protest Rule That Could Bring Down Trump. Social media posts from protest groups broke down the rule and its limitations.