In L.A., home to the biggest population of Iranians outside of Iran, a throng of protesters formed a slow-moving procession along blocks of a closed downtown street.
They chanted for the fall of Iran's government and waved hundreds of Iranian flags that turned the horizon into an undulating wave of red, white and green.
"We want freedom," they thundered.
"I'm Iranian American and I'm sick and tired of what's happening in my home country," said Mike Kazerouni, a local attorney who attended Saturday's protests. "I just want to be a voice of the Iranian people to amplify their voice for freedom and human rights."
Nasim Pedrad, an Iranian American actress, writer, and comedian who is best known for her time on Saturday Night Live, marched alongside protesters in L.A. She posted a photo on Instagram with the caption, "Forever w the people of Iran."
Iran's nationwide antigovernment protest movement first focused on the country's mandatory hijab covering for women following Amiri's death on Sept. 16.
The demonstrations there have since transformed into the greatest challenge to the Islamic Republic since the 2009 Green Movement over disputed elections. In Tehran on Saturday, more antigovernment protests took place at several universities.
Iran's security forces have dispersed gatherings in that country with live ammunition and tear gas, killing over 200 people, including teenage girls, according to rights groups.
The Biden administration has said it condemns the brutality and repression against the citizens of Iran and that it will look for ways to impose more sanctions against the Iranian government if the violence continues.
Between chants, protesters in D.C. broke into song, singing traditional Persian music about life and freedom - all written after the revolution in 1979 brought religious fundamentalists to power in Iran. They sang one in particular in unison - "Baraye," meaning because of, which has become the unofficial anthem of the Iran protests. The artist of that song, Shervin Hajipour, was arrested shortly after posting the song to his Instagram in late September. It accrued more than 40 million views.
"Because of women, life, freedom," protesters sang, echoing a popular protest chant: "Azadi" - Freedom.
The movement in Iran is rooted in the same issues as in the U.S. and around the globe, said protester Samin Aayanifard, 28, who left Iran three years ago. "It's forced hijab in Iran and here in America, after 50 years, women's bodies are under control," said Aayanifard, who drove from East Lansing, Michigan to join the D.C. march. She referred to rollbacks of abortion laws in the United States. "It's about control over women's bodies."
Several weeks of Saturday solidarity rallies in the U.S. capital have drawn growing crowds.
"We're here for you," said Arezo Rashidian to the people of Iran. She's a Southern California health care professional and one of the organizers of Saturday's L.A. protests. "We're a voice. We will be your internet. We will be your media. We are here for regime change. We are here to say not to JCPOA (Joint Comprehensive Plan of Action). The United States cannot make a deal with Iran. They are a threat to the world. We are here to be your voice."
The Associated Press contributed to this report.