(CNN) Americans young and old took to the streets of US cities Saturday to say "Families Belong Together" nearly two months after the Trump administration implemented its "zero tolerance" policy toward undocumented immigrants, prompting the separation of thousands of children from their parents.

The main rally was in Washington, DC, but hundreds of marches, protests and rallies took place across the country in cities like New York, Philadelphia, Chicago, Milwaukee, Denver, Miami, St. Louis, San Francisco and Los Angeles, where crowds called forthe immediate reunification of migrant families and an end to family detentions and separations.

According to organizers, protesters have three demands:

• They want separated migrant families to be reunited immediately.

• They want the government to end family detentions.

• And they want the Trump administration to end its zero tolerance policy.

Attendees in Washington braved the summer heat and marched from Lafayette Square to the White House -- though the President is at his golf resort in New Jersey -- and down Pennsylvania Avenue, past the Trump Hotel, where chants of "Shame! Shame! Shame!" broke out.

In Atlanta, demonstrators carried cages with dolls inside, and marchers in Chicago encouraged each other to "fight back."

Protesters in Houston chanted, "No baby jails," outside City Hall. Farther to the south, crowds gathered in McAllen, Texas, the border town where one of the Customs and Border Protection agency's processing detention centers sits.

Several celebrities joined the rally in Los Angeles, like singer-songwriter John Legend, who sang his song "Preach," and Cher, who encouraged people to go vote in November.

Many attendees carried signs, some demanding a change to the administration's policy, others celebrating the contributions that immigrants make to the country.

"We are all immigrants," one said.

"Seeking safety is not a crime," said another.

"Let our children dream. Let them go!" a sign in Washington said.

Activists protest the "zero tolerance" policy Saturday in Lafayette Square near the White House.

"I'm outraged that families are being separated," said Margaret Stokes, 54, a Virginia teacher protesting in the nation's capital. She carried a sign that asked, "Where are the children?"

"Separating families, especially young children, without a plan to reunite them is abhorrent," Stokes said. "This is not America.

"We need to let the administration know that we will not become numb to these atrocities."

She said she brought her 5-year-old son, Aaron, to Saturday's protest in Washington to show him she doesn't want to be a part of an America like that. She said the policy indicates the country has "no morals," adding that "the GOP claims to be pro-life but is stealing babies from their family."

But Saturday's protests drew people from both sides of the aisle.

"It's unconscionable, immoral. None of the words are quite strong enough," said Allison Thompson, 49, a lawyer from Fayetteville, North Carolina. She said she was a registered Republican attending her first protest.

"Separating a child from a parent -- as a parent -- is the most inhumane thing ever," the mother of two said. "There is just nothing worse to me."

The crisis has been building for weeks

More than 2,500 undocumented children were separated from their parents in the weeks since the zero-tolerance policy took effect. Under the policy, any adult caught crossing the border illegally faced prosecution, and their children were sent to federal shelters all over the United States.

Outrage over the separations has been at a fever pitch for weeks. The anger hasn't abated either, even after President Donald Trump signed an executive order June 20 reversing the family separation policy.

JUST WATCHED 6 migrant children reunited with parents Replay More Videos ... MUST WATCH 6 migrant children reunited with parents 01:08

A federal judge this week ordered a halt to most family separations at the border and the reunification of families. Within 14 days, children under 5 were to be back with their parents, and within 30 days, children 5 and older were to be reunited with theirs.

But Families Belong Together protesters don't want to wait.

Protesters share why they're in the streets

Jose Flores, a 34-year-old protester in Washington, posted a picture of his daughter Isabella on Instagram, flanked by signs supporting immigrants. He told CNN about his father who came to the United States illegally from Guatemala more than three decades ago.

"With a little luck and some persistence he was able to get his papers and brought us to the USA in 1987," Flores said. "He passed away in 2000 a homeowner, business owner and citizen.

"That is why I march today, to honor his sacrifice. And to teach my daughter of the same sacrifice."

Diane Norris of Mission, Texas, joined the protests in McAllen. Her sign said, "Now you've pissed off grandma."

"I know what it's really like down here and how scared and desperate the refugees are," she told CNN via Instagram. "Trump's policy is cruelty personified and we ALL need to speak out against it."

MacKenzie Banks, 19, carried a sign at the Washington protest that read, "If these children lived in my uterus would y'all start caring."

Rise and resist. #FamiliesBelongTogether A post shared by MacKenzie Banks (@_mackiebanks) on Jun 30, 2018 at 7:02am PDT

"I am protesting in DC today because I cannot turn a blind eye to the clear human rights abuses brought forth by this administration," Banks told CNN. "They deserve to be held accountable for the atrocities they are committing against our brothers and sisters."

Crowds in Washington also heard from the immigrant communities most directly affected by the Trump administration's policies and rhetoric.

A 12-year-old girl named Leah, the daughter of undocumented immigrants, stepped up to the podium and spoke about living in fear of "losing my mom to deportation."

JUST WATCHED 12-year-old gives powerful speech Replay More Videos ... MUST WATCH 12-year-old gives powerful speech 05:01

"I don't like to live with this fear," she said through tears streaming down her face. "It's scary. I can't sleep. I can't study. I am stressed.

"I am afraid that they will take my mom away while she is at work, out driving or at home," she continued. "I don't understand why this administration won't support mothers who just want a better life for their children."

'This is beyond politics'

Event organizers said Saturday's protests were about addressing an ethical issue.

"This is not left or right," said Anna Galland, executive director of MoveOn.org, one of the organizations leading Saturday's protests. "It is right and wrong."

Galland said she and US Rep. Pramila Jayapal put out a call for protests less than two weeks ago, and they were "overwhelmed" by the response.

Rallies were to take place in 750 cities big and small all over the country, Galland said.

Photos: Immigration protests around the country Salt Lake City: Activists hold signs Saturday to protest the Trump administration's approach to illegal border crossings and separation of children from immigrant parents. Hide Caption 1 of 16 Photos: Immigration protests around the country Chicago: Protesters fill Daley Plaza to listen to speakers and show opposition to the White House's immigration policies. Hide Caption 2 of 16 Photos: Immigration protests around the country Los Angeles: A woman attends a protest outside the Metropolitan Detention Center, after marching to decry Trump administration immigration and refugee policies. Hide Caption 3 of 16 Photos: Immigration protests around the country Indianapolis: An activist holds a poignant protest sign at the Indiana Statehouse. Hide Caption 4 of 16 Photos: Immigration protests around the country Los Angeles: A woman with "we care" written on her hands lifts them up at a protest outside the Metropolitan Detention Center. Hide Caption 5 of 16 Photos: Immigration protests around the country New York: People march across the Brooklyn Bridge in support of families separated at the border. Hide Caption 6 of 16 Photos: Immigration protests around the country Chicago: A young girl holds a sign as she takes part in the protest. Hide Caption 7 of 16 Photos: Immigration protests around the country Washington: A protester reacts to speakers in a crowded Lafayette Square across from the White House. Hide Caption 8 of 16 Photos: Immigration protests around the country Boston: US Sen. Elizabeth Warren of Massachusetts speaks at the rally while a protester holds the flag of El Salvador in the foreground. Hide Caption 9 of 16 Photos: Immigration protests around the country New York: Activists shout at the rally to end family separation. Hide Caption 10 of 16 Photos: Immigration protests around the country Casper, Wyoming: People write letters to members of the Wyoming congressional delegation following an immigration rally in Pioneer Park. Hide Caption 11 of 16 Photos: Immigration protests around the country Washington: Protesters, many of them holding signs, gather in Lafayette Square across from the White House. The sign in the foreground translates as "families belong together." Hide Caption 12 of 16 Photos: Immigration protests around the country New York: A protester marches across the Brooklyn Bridge. Hide Caption 13 of 16 Photos: Immigration protests around the country Austin, Texas: A demonstrator uses baby clothes to spell out the word "reunite" during a rally against the Trump administration's immigration policies outside the Texas Capitol. Demonstrations are being held in cities across the United States on Saturday to call for the reunification of separated families and to protest the detention of children and families seeking asylum at the border. Hide Caption 14 of 16 Photos: Immigration protests around the country Albuquerque, New Mexico: A protester holds a sign as demonstrators gather downtown at Civic Plaza calling for an end to family separation. Hide Caption 15 of 16 Photos: Immigration protests around the country New York: Demonstrators at Foley Square raise their fists in protest. Hide Caption 16 of 16

"I think if you asked someone on the street, 'Is it a political question whether we should tear babies out of their mother's arms?' they would say, 'No, that's a moral question,' " Galland told CNN's Christi Paul. "And this is a moment of moral outrage."

Jayapal, who was also arrested during the protest at the Senate office building earlier this week, agreed.

"This is beyond politics," the Washington state Democrat said Saturday morning. According to her, the rallies are about keeping the issue "at the front of the agenda" and sending a message to Trump that he can change his policy immediately.

"You don't put kids in cages," she said. "You don't separate breastfeeding babies from their mothers. You don't put asylum-seekers in prison, and we're calling for an end to that today."

Protesters rally against the Trump administration's immigration policies Saturday in New York.

Sen. Elizabeth Warren also echoed that sentiment at a rally in Boston.

"This moment is a moral crisis for our country," the Massachusetts Democrat said.

"We will not be silent. We cannot be silent. We will build a country that reflects our values. That is why we are here."