Advocacy groups, activists and local residents gathered with signs that called for President Donald Trump's impeachment.
More than 2,000 immigrated children still remain separated from their parents.
Thousands of people are expected to attend the "Families Belong Together" march and rally Saturday in downtown D.C.
The US president defended his policy of separating children from their families who have been illegally crossing the southern US-Mexico border, saying, to prosecute parents for illicit entry, "you have to take the children away". "It's been incredibly heartbreaking to see children being held in detention centers and being put in court rooms by themselves".
Lin-Manuel Miranda, the creator of the musical "Hamilton, " sang a lullaby dedicated to parents who are unable to sing to their children. "We will also have posters, signs and shirts that commemorate Americans who have been killed by illegal aliens".
"We are better than this, " one said.
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Nonetheless, the 31-year-old Barcelona striker says he is committed to his side's cause and isn't anxious about external factors. He was part of the Portugal team that made the semi-finals in 2006, and now has faced round of 16 exits in both 2010 and 2018.
After the rally, at least 200 of the protesters continued the march to Portland's regional Immigration and Customs Enforcement office on SW Macadam Ave, where they joined the group of protesters who've been camping out next to the facility for almost two weeks.
In the president's hometown of New York City, an estimated 30,000 marchers poured across the Brooklyn Bridge in sweltering 90-degree heat, some carrying their children on their shoulders, chanting, "Shame!"
For people on both sides of the political aisle, Saturday morning's demonstration was the aftermath of jarring images illustrating reality - children being separated from their families at the border and little indication on when they will be reunited.
More than 700 events were planned in cities across the US, according to organizers.
It's one of several dozen happening across the country.
Trump agreed to rescind the separation part of the policy, but opponents say the administration has no plan for the speedy reunification of those families.
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Police suspect they committed suicide after the family suffered financial losses in business. The house has been barricaded and the police were questioning the neighbours.
"Protests are great, but this fight doesn't stop here", said Jama.
"It's upsetting. Families being separated, children in cages", said Emilia Ramos, a cleaner in the district, fighting tears at the rally.
Rita Montoya, 36, a Washington lawyer, was born in California but has Mexican origins and arrived at the protest with her two sons, aged four and two. Using the app resistbot, she instructed the crowd to share their feelings with whoever represents them in Congress, regardless of party lines.
Nora Martinez (left) migrated with her mother to the United States as a child, and said Trump's policies hit particularly hard now that she has her own daughter.
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. He said during his speech that the "zero-tolerance" policy is devastating his family, friends and colleagues.
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The thief or thieves reportedly used the account to purchase savings bonds with Treasury Direct, the report says. Members of the public helped celebrate, including Austin Mayor Steve Adler and Austin Police Chief Brian Manley.