In Washington, D.C., another massive crowd gathered in Lafayette Park across from the White House in what was expected to be the largest protest of the day, stretching for hours under a searing sun. Firefighters at one point misted the crowd to help people cool off.

Lin-Manuel Miranda, creator of the musical "Hamilton," sang a lullaby dedicated to parents unable to sing to their children. Singer-songwriter Alicia Keys read a letter written by a woman whose child had been taken away from her at the border.

"It's upsetting. Families being separated, children in cages," said Emilia Ramos, a cleaner in the district, fighting tears at the rally. "Seeing everyone together for this cause, it's emotional."Around her, thousands waved signs: "I care," some read, referencing a jacket that first lady Melania Trump wore when traveling to visit child migrants. Her jacket said, "I really don't care, do U?" and it became a rallying cry for protesters Saturday.