In Parkland, Florida, Sari Kaufman was among students from Marjory Stoneman Douglas High School - where the mass shooting took place - who urged peers to get involved in politics, register to vote and turf out lawmakers who did not protect them.
After brief remarks at City Hall from march organizer Kari Siegenthaler, one of three Liberal Arts and Sciences Academy students who planned the event, marchers walked down Congress Avenue to the Capitol. That march saw an estimated 450,000 to a million attendees, although those figures have always been in dispute.
Aspen Stelly says she has personal experience with what she says are lax gun regulations not being enforced.
Former Beatle Sir Paul joined demonstrators in NY while Hollywood star George Clooney and his British wife Amal were among those marching on Washington.
"One of my best friends was killed in gun violence right around here, so it's important to me", the music legend told CNN, while wearing a shirt that said, "We Can End Gun Violence". The demonstration was inspired by students in Parkland, Florida - survivors of last month's school attack that killed 17.
The largest protest was in Washington, the largest gun control rally in the United States since the Million Mom March in 2000.
Chanting "no more silence, end gun violence" as they marched north from Nathan Phillips Square along University Avenue toward Queen's Park, Members of Communities for Zero Violence, which organized the Toronto rally, stopped with the crowd for a moment of silence in front of the USA consulate. "All they're doing is asking the government to take their liberty away from them without due process", Mr Brandon Howard, a 42-year-old Trump supporter, said of the protesters in the capital.
"People from all sorts of generations are coming to fight for us and with us", said Merkel.
Me and my friend Carter led a walkout at our elementary school on [March 14].
The young activist said that for those who could not comprehend the importance of urgent gun reform, it is simple. During the march, counterprotesters and marchers shouted at each other and police had to step in to keep the peace.
Among those speaking in Washington was Yolanda Renee King, the nine-year-old granddaughter of the Rev Martin Luther King.
"It's completely unacceptable that we are exercising our rights to be safe at school", Naomi said in front of a sea of people.
In the western coast city of San Francisco, thousands of people demonstrated to advocate for gun control.