An overlay of a high-resolution photograph of the Women's March shows crowd density. Red areas are the highest density, followed by orange and yellow. In all the photo suggests about 440,000 people attended the march. Digital Design & Imaging Service hide caption
Demonstrators protest during the Women's March on Washington in D.C. Joshua Lott/AFP/Getty Images hide caption
The Apgar family: The mother Ruth (center) is flanked by daughters Kristina (L) and Samantha (R) at the Women's March on Saturday in Washington, D.C. Sarah McCammon/NPR hide caption
Demonstrators bear their signs at the women's march in Barcelona, Spain. The Spaniards drew inspiration from the Women's March on Washington, but due to the time difference, they actually hit the streets before the Americans. David Ramos/Getty Images hide caption
Sarah and her mom, Tamara, traveled from Detroit to be at the Women's March on Washington. Meg Kelly/NPR hide caption
Protesters hold up their handmade signs as they prepare for the Women's March on Washington. Hansi Lo Wang/NPR hide caption
Duncan Green, author of "How Change Happens." He says of activism: "There has to be a little part of you that acknowledges doubt, ambiguity and uncertainty. You have to have room to change direction." Ben de la Cruz/NPR hide caption