More than 700 planned marches are expected to draw hundreds of thousands of people across the country, from immigrant-friendly cities like Los Angeles and New York to conservative Appalachia and Wyoming under the banner Families Belong Together.
Thousands dressed in white and gathered early Saturday morning in sweltering 90-degree heat in Lafayette Park across from the White House in what was expected to be the largest of the day's protests.
"What's next? Concentration Camps?" one marcher's sign read. "I care, do you?" read another, referencing a jacket the first lady wore when visiting child migrants amid the global furor over the administration's zero-tolerance policy that forced the separation of more than 2,000 children from their parents. Her jacket had "I really don't care. Do you?" scrawled across the back, and that message has become a rallying cry for Saturday's protesters.
"We care!" marchers shouted outside city hall in Dallas. Organizer Michelle Wentz says opposition to the administration's "barbaric and inhumane" policy has seemed to cross political party lines. Marchers carried signs that read "Compassion not cruelty" and "November is coming."
In New York City, thousands began chanting "shame!" and singing "shut detention down!" before their planned march across the Brooklyn Bridge.
Smaller groups came together in city parks and downtown squares in every state, a total of 703 places across the country, and photos quickly started ricocheting around social media.
Some carried tiny white onesies. "What if it was your child?" was written on one. "No family jails," said another.
Children joined in. A little girl in Washington, D.C., carried a handwritten sign: "I get my mommy. Why can't she?"
Though many who show up to the rallies across the country will be seasoned anti-Trump demonstrators, others are new to immigration activism, including parents who say they feel compelled to show up after heart-wrenching accounts of children forcibly taken from their families as they crossed the border illegally. In Portland, Oregon, for example, several stay-at-home moms have organized their first rally while caring for young kids.
"I'm not a radical, and I'm not an activist," said Kate Sharaf, a Portland co-organizer. "I just reached a point where I felt I had to do more."
Immigrant advocacy groups say they're thrilled - and surprised - to see the issue gaining traction among those not tied to immigration.
"Honestly, I am blown away. I have literally never seen Americans show up for immigrants like this," said Jess Morales Rocketto, political director at the National Domestic Workers Alliance, which represents nannies, housekeepers and caregivers, many of whom are immigrants. "We just kept hearing over and over again, if it was my child, I would want someone to do something."
Saturday's rallies are getting funding and support from the American Civil Liberties Union, MoveOn.org, the National Domestic Workers Alliance and The Leadership Conference. But local organizers are shouldering on-the-ground planning, many of them women relying on informal networks established during worldwide women's marches on Trump's inauguration and its anniversary.
Tyler Houlton, a spokesman for the U.S. Department of Homeland Security, welcomed interest in the immigration system and said only Congress has the power to change the law.
"We appreciate that these individuals have expressed an interest in and concern with the critical issue of securing our nation's borders and enforcing our immigration laws," Houlton said. "As we have indicated before, the department is disappointed and frustrated by our nation's disastrous immigration laws and supports action."
Trump took to Twitter on Saturday morning to show his support for Immigration and Customs Enforcement amid calls from some Democrats for major changes to immigration enforcement.
Tweeting from New Jersey, Trump said that Democrats "are making a strong push to abolish ICE, one of the smartest, toughest and most spirited law enforcement groups of men and women that I have ever seen." He urged ICE agents to "not worry or lose your spirit."
In Portland, Sharaf and other mothers who organized the rally hope to attract 5,000 people.
Right-wing activists with the group Patriot Prayer also have a permit to march later in the day Saturday and the Portland Police Bureau said Friday they planned to have a heavy police presence.
Sharaf and co-organizer Erin Conroy have coordinated with immigrant advocacy groups.
"This is not my wheelhouse," Conroy said. "As far as I'm concerned, this is a national emergency that we all need to be focused on right now."
Immigration attorney Linda Rivas said groups have met with U.S. authorities, congressional representatives and other leaders to discuss an escalating immigration crackdown that they say began decades ago. But the family separation policy has been a watershed for attracting a broader spectrum of demonstrators, she said.
"To finally have people on board wanting to take action, marching, taking to the streets," Rivas said. "It's been motivating for us as advocates because we have to keep going."