Tens of thousands of people marched in demonstrations across the United States on Saturday to protest President Donald Trump’s zero tolerance stance on illegal immigration that has led to children being separated from their families and housed in cages and tents.

Trump tweeted later Saturday that the country’s immigration laws are “the dumbest anywhere in the world” and that immigrants should be sent back to their countries without the benefit of due process of the law.

When people come into our Country illegally, we must IMMEDIATELY escort them back out without going through years of legal maneuvering. Our laws are the dumbest anywhere in the world. Republicans want Strong Borders and no Crime. Dems want Open Borders and are weak on Crime! — Donald J. Trump (@realDonaldTrump) June 30, 2018

A coalition of activists, including groups that organized the massive women’s marches the past two years, helped to coordinate more than 600 demonstrations in major cities and small towns, in the nation’s capital, in Hawaii and Puerto Rico, on the international bridge between El Paso, Texas, and Juarez, Mexico, and even in Antler, North Dakota, population 27.

Sen. Elizabeth Warren, D-Mass., waves to the crowd Sen. Elizabeth Warren, D-Mass., waves to the crowd from the back of a pickup truck prior to speaking at the Rally Against Separation, June 30, 2018, in Boston. Sen. Elizabeth Warren, D-Mass., waves to the crowd from the back of a pickup truck prior to speaking at the Rally Against Separation, June 30, 2018, in Boston.

Organizers say they received strong support from mothers who are opposed to the Trump administration’s previous policy of separating children from their parents at the U.S.-Mexico border. Several stay-at-home moms organized Saturday’s rally in Portland, Oregon.

In Washington, a 12-year-old girl named Leah, whose parents are undocumented immigrants who could face deportation, delivered an impassioned message to all child immigrants.

“I want to tell kids at the border and all over the country not to give up and fight for their families. We are all humans and deserve to be loved and cared for! We are children!” she told the cheering crowd.?

WATCH: Thousands Protest Trump's Zero Tolerance Policy on Illegal Immigration

The Reverend Traci Blackmon, senior pastor of The King United Church of Christ in Florissant, Missouri, told the Washington crowd, “We have been this way before. And we must not forget. We must always remember that this is not as much about safe immigration policy as it is about separatist ideology.”

Also in Washington, Lin-Manuel Miranda, the creator of the musical “Hamilton,” sang a lullaby that was dedicated to the parents who are unable to sing to their children who have been taken away from them.

Margarita Perez of Albuquerque, with her daughter Margarita Perez of Albuquerque, with her daughter by her side, holds up a Mexican flag during a protest on Civic Plaza in Albuquerque, N.M., June 30, 2018. Perez was among thousands who gathered on the plaza to voice their opposition to U.S. immigration policies and President Donald Trump. Margarita Perez of Albuquerque, with her daughter by her side, holds up a Mexican flag during a protest on Civic Plaza in Albuquerque, N.M., June 30, 2018. Perez was among thousands who gathered on the plaza to voice their opposition to U.S. immigration policies and President Donald Trump.

Protesters in New York, Trump’s hometown, chanted “No hate, no fear, immigrants are welcome here!” in the sweltering heat at a Manhattan park before marching across the Brooklyn Bridge to a plaza in the borough of Brooklyn. As they marched over the bridge, many of them chanted “shame.” Drivers honked their horns in support.

“It’s important for this administration to know that these policies that rip apart families — that treat people as less than human, like they’re vermin — are not the way of God, they are not the law of love,” said Julie Hoplamazian, an Episcopal priest marching in Brooklyn.

Activists hold signs to protest the Trump administ Activists hold signs to protest the Trump administration's approach to illegal border crossings and separation of children from immigrant parents, June 30, 2018, in Salt Lake City. Activists hold signs to protest the Trump administration's approach to illegal border crossings and separation of children from immigrant parents, June 30, 2018, in Salt Lake City.

In Los Angeles, singer John Legend sang to the crowd and U.S. Representative Maxine Waters called for the president’s impeachment.

Hundreds of protesters gathered in downtown Dallas, Texas, and chanted “We care” outside city hall.

Protesters gather near a U.S. Customs and Border P Protesters gather near a U.S. Customs and Border Protection station to speak out against immigration policy, June 30, 2018, in McAllen, Texas. Protesters gather near a U.S. Customs and Border Protection station to speak out against immigration policy, June 30, 2018, in McAllen, Texas.

Saturday’s rallies, which were called Families Belong Together, received funding and support from several large organizations, including the American Civil Liberties Union and MoveOn.org.

FILE - People hold signs as they participate in th People hold signs as they participate in the "Families Belong Together: Freedom for Immigrants" march, June 30, 2018, in Los Angeles. People hold signs as they participate in the "Families Belong Together: Freedom for Immigrants" march, June 30, 2018, in Los Angeles.

Under Trump’s zero tolerance policy, the government has begun prosecuting all migrants caught entering the country illegally. Trump has halted his policy of taking children from their detained parents after increasing public pressure.

According to the Department of Homeland Security, 2,047 children remain separated. Officials say more than 500 children have been reunited with their families.

Trump administration officials have said repeatedly they know where all the separated children are, although that has been disputed by attorneys and advocates.