By any measure, millions of people participated in the women’s marches that took place across the country and around the world on Saturday in opposition to President Donald Trump. Exactly how many millions is difficult to pin down since large crowds are notoriously tough to count, but a pair of researchers place the figure at at least 3.3 million just in the U.S., based on hundreds of news reports and Facebook data. Or maybe it was 4.6 million.