WASHINGTON — Hundreds of marches took place across the United States on Saturday as thousands of people demanded the Trump administration reunite families separated at the U.S.-Mexico border.

The protests, marching under the banner "Families Belong Together," are hoping to push the Trump administration to reunite thousands of immigrant children separated from their families after crossing into the United States.

More than 600 marches occurred throughout the country, from liberal, immigrant-friendly cities like New York and Los Angeles to more conservative regions like Appalachia and Wyoming. American expats even gathered across from the U.S. consulate in Munich.

Immigration activists march toward the U.S. Capitol to protest the Trump Administration's immigration policy in Washington on June 30, 2018. Joshua Roberts / Reuters

As approximately 30,000 people marched across the Brooklyn Bridge in New York City, they chanted, "Immigrants built this bridge." When they got to the city's ICE headquarters, protesters yelled "shame" at the building.

Closest to the situation were the thousands who gathered on the border with Mexico, particularly in El Paso, Texas.

Four-year-old Belinda and her native dance group Danza Matachin San PIO X help lead the Women's March in El Paso, Texas on June 30, 2018. Sumiko Moots / NBC News

Thousands watched the Facebook livestream of the "Families Belong Together" rally in Washington where parents, children and faith leaders took turns to speak out against the Trump administration policy. Lin-Manuel Miranda took the stage and sang a song from his celebrated musical "Hamilton" to the protesters.

"We will not stand for a country separating children from their families," Miranda told MSNBC. "And if you are silent on that issue, or you are somehow for that issue you're not getting re-elected. And that's what we need to make them understand."

Meanwhile, civil rights icon Rep. John Lewis, D-Ga., reminded demonstrators in Atlanta of how effective the rallies he organized in the 1960s were in combating segregation and inequality. This was another moment in which to fight back, he said.

"As a nation and a people we can do better," Lewis said. "Don’t give up. Don’t give in. Keep marching."

The congressman urged attendees to vote in the upcoming election to stymie the administration and future policies, and the crowd responded with a chant of "vote, vote, vote."

More than 2,300 children were taken from their families in recent weeks under the Trump administration's "zero tolerance" policy in which people entering the U.S. illegally face being prosecuted. But after public outcry earlier this month, President Donald Trump ordered that the families crossing into the country illegally no longer be separated.

However, more than 2,000 children still remain separated from their parents. Saturday's marches hope to put pressure on the administration to reunify these families as quickly as possible.

Demonstrators lifted their fists and numerous, colorful signs. A 4-year-old in Washington D.C. raised one that read "I get my mommy. Why can't she?" A New Yorker raised a sign that said "Amerikkka: separating families since 1619." In El Paso, Texas, another said, "I really do care. Do you?” a reference to the jacket worn by first lady Melania Trump last week as she headed for the border to visit children separated from their families.

Iliana Pech Cruz came to the Washington rally because she is a DACA recipient from Mexico, who came to the United States as an infant. She drove from her home in North Canton, Ohio.

"I'm here to fight for everybody that deserves the rights in this country," she said. "We'll come when Trump is here, when he's not, when he's vacationing on his golf course, it doesn't matter where he is because we're here to fight. I'm not afraid of what might happen to DACA recipients. My parents taught me never to walk in fear."

Demonstrators participate in "Keep Families Together" march to protest Trump administration's immigration policy in Manhattan, New York on June 30, 2018. Shannon Stapleton / Reuters

More than 100 protesters gathered outside the Trump National Golf Club in Bedminster, New Jersey, where the president is spending the weekend.

On the way, we passed a group of more than 100 protesters gathered in a grassy area at the closest major intersection to the property, about two and a half miles from the entrance.

Cristina Jimenez, co-founder and Executive Director of United We Dream, the largest immigrant youth-led organization in the country, hopes the Families Belong Together march will mobilize the fight against the administration’s criminalization of immigrant communities.

“This is the critical moment to mobilize the community, mobilize the entire country and people of conscience who are looking at the media and understanding more of what this country is doing, particularly ICE and deportation agents, and we want to take a stand together with the rest of the country," Cristina Jimenez, co-founder and executive director of United We Dream, largest immigrant youth-led network in the country, told NBC News.

Jimenez said her organization is asking "Congress to stop Trump’s deportation force and ensuring that as the administration asks for more money to target community with ICE and border patrol agents, we say no and abolish and defund them.”

Trump was already tweeting about immigration in the hours leading up to the march, referencing a growing call from immigration advocates to abolish U.S. Immigration and Customs Enforcement.

The 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. I have watched ICE liberate towns from the grasp of MS-13 & clean out the toughest of situations. They are great! — Donald J. Trump (@realDonaldTrump) June 30, 2018

To the great and brave men and women of ICE, do not worry or lose your spirit. You are doing a fantastic job of keeping us safe by eradicating the worst criminal elements. So brave! The radical left Dems want you out. Next it will be all police. Zero chance, It will never happen! — Donald J. Trump (@realDonaldTrump) June 30, 2018

"The 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. I have watched ICE liberate towns from the grasp of MS-13 & clean out the toughest of situations. They are great!" Trump tweeted.

In a follow-up tweet, Trump urged the men and women of ICE not to worry about the ongoing calls to abolish the department.

"You are doing a fantastic job of keeping us safe by eradicating the worst criminal elements. So brave! The radical left Dems want you out. Next it will be all police. Zero chance, It will never happen!" he wrote.

Rallies against Trump's immigration policy have sprung up in the weeks since its implementation, but Saturday's could be among the largest yet and have received funding and support from the American Civil Liberties Union, MoveOn.org, the National Domestic Workers Alliance and The Leadership Conference. Local organizers have coordinated on-the-ground planning, and many have relied 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.”

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.”