Students from across the country are expected to take to the streets Saturday in a nationwide march against gun violence, about a month after 17 people were killed during a mass shooting at a Florida high school.
>> READ MORE: Live updates from the marches in Philly and D.C.
"March for Our Lives," an event spearheaded by survivors of the Feb. 14 shooting at Marjory Stoneman Douglas High School in Parkland, is expected to bring huge crowds to Washington to rally over gun issues and school safety. "Sibling marches" are being held in cities across the United States, including Philadelphia.
Here's what you need to know ahead of time.
What is “March for Our Lives”?
The "for kids and by kids" event in Washington will be held March 24 on Pennsylvania Avenue between Third and 12th Streets Northwest, beginning at noon.
The event is expected to draw hundreds of thousands of participants, according to the Washington Post. More than 800 sibling marches, which are also student-led initiatives, according to the march's website, are expected to be held across the country, including in Philadelphia.
The march was organized to "end the epidemic of mass shootings," according to the event's Twitter profile.
Survivors of the Parkland shooting recently appeared on The Ellen DeGeneres Show to promote the event.
"You know, the thing that inspired us to create the march was people saying, 'You are all talking about gun control, and this is not the time to talk about gun control. This is the time to grieve, a time to mourn.' And we understand that," Cameron Kasky, a survivor of the Parkland shooting, said on the show. "And we said, now might not be the time to talk about gun control, here's the time to talk about gun control — March 24."
The mission statement on the march's website says that while "school safety is not a political issue," the focus of the event is "to demand that a comprehensive and effective bill be immediately brought before Congress to address these gun issues."
The website reads: "No special interest group, no political agenda is more critical than timely passage of legislation to effectively address the gun violence issues that are rampant in our country."
A handful of celebrities, including Oprah Winfrey and George and Amal Clooney, have donated to the event's funding efforts.
What do I need to know about the Philadelphia event?
Philadelphia's sibling march will happen on the same day, March 24, kicking off around 9:30 a.m. at Fifth and Market Streets where thousands expected to attend will snake through Old City before ending up at Lombard Circle along Columbus Boulevard. Speakers include Sen. Bob Casey (D, Pa.), Mayor Kenney and Jami Amo, a Columbine High School massacre survivor, as well as other activists and representatives from other groups.
Three student march leaders, two in high school and one who is a senior at the University of Pennsylvania, are organizing Philly's event, said Gigi Peterkin, a spokeswoman for the march.
"The fact that this march and movement called for legislative action, that appealed to them," she said.
Organizers submitted a permit application to the Office of Special Events, city spokeswoman Ajeenah Amir confirmed. The Philadelphia Police Department said it was aware of the event.
A GoFundMe page for the Philadelphia event had raised more than $10,600 of its $50,000 goal as of Wednesday morning. About 3,400 people are "going" to the event, according to the Philadelphia march's Facebook page.
What is going on in the suburbs?
A "Suburban Support for the March for Our Lives" has also been organized by Indivisible Chester County and State Sen. Daylin Leach (D., Montgomery), according to its Facebook event page. But that march also will be held in Philadelphia, beginning at Independence Hall, at 10 a.m.
Marches are also planned throughout New Jersey, including in Haddon Heights, Ocean City, and Princeton.
What about bus trips to D.C.?
Bus trips to Washington and marches in other major cities are being organized across the country. But it may be too late to save a seat if you haven't done so already.
The Lutheran Episcopal Advocacy Ministry of New Jersey is organizing bus trips to Washington, departing from Marlton, Montclair, Newark and Hamilton Square. The trip is $25 for adults and $15 for teens 13 to 18.
The ministry quickly filled up four buses but added two more, the Rev. Sara Lilja said. Registration has closed.
"Anything we can do to eliminate sources of violence is critical in our understanding of what it means to be a faithful person of God," Lilja said.
Bryn Mawr College is also organizing a bus trip for students, faculty, and staff.
What sparked all of this?
Fourteen students and three staff members were killed at Douglas High after gunman Nikolas Cruz, 19, opened fire on his classmates with an AR-15 on Feb. 14, one of a growing list of mass shootings in the United States.
Politicians, activists, and school-shooting survivors quickly began calling for gun reform. Emma Gonzalez, a senior at Douglas, led hundreds in chants of "no more guns" and "not one more" during a large rally days after the shooting.
Students have since met with Florida Sen. Marco Rubio (R., Fla.), President Trump, and Dana Loesch, a spokeswoman for the National Rifle Association, to address their concerns.
Earlier this month, the Florida House passed a school-safety bill that is now awaiting approval from Gov. Rick Scott. The march is an outgrowth of efforts to raise awareness about gun violence and school safety.
In another event planned as a result of the Florida school shooting, some students and teachers in the region walked out of classes for 17 minutes last week, part of a nationwide observance on the one-month anniversary.