Martin was wearing a hoodie pulled up over his head when he was shot and killed by Neighborhood Watch participant George Zimmerman on Feb. 26 as the teen walked back to his father's house in a gated community in Sanford, Fla., from a convenience store. The unarmed Martin was carrying a bag of Skittles candy and a container of iced tea. Police, who had possession of Martin's cellphone after he was killed, did not notify his family. No charges have been filed against Zimmerman.
Many say Zimmerman, 28, who has a white father and Hispanic mother, would not have targeted Martin if the teen had been white and wearing a hoodie.
Yet talk show host Geraldo Rivera argued that Martin was partly responsible for his death because he was wearing a hoodie. Rivera's comments have drawn rebuke, even from his own son.
The appearance of racial profiling in the case has evoked renewed fear among the parents, relatives, and friends of black and biracial boys.
"A white boy wears a hoodie and he's a college student; a black man wears a hoodie and he's a professional thug," said Chuck Williams, director of Drexel University's Center for the Prevention of School-Aged Violence. "This apparel makes me a criminal, and I am in their eyes. What I wear gives them an excuse to do what they want to me."
Hence the spreading call to hoodie action, which started over Facebook and Twitter and gained momentum in the last week as celebrities from singer Common to the entire Miami Heat basketball team released photos of themselves wearing hoodies. Philadelphia District Attorney Seth Williams even donned a black hoodie and posted on Facebook a photo of himself wearing it.
Philadelphia's march Friday followed similar events in New York, Los Angeles, and Miami. And the protests show no sign of slowing. Hoodie candlelight vigils are scheduled for LOVE Park on Monday and Thursday. On Sunday, protesters in hoodies plan to gather at Temple University.
Parents of black children who once warned them to keep their hoodies down so they would not be wrongfully profiled are now saying enough is enough.
"I urge all parents to tell their children to wear hoodies as much as they can. What are they going to do, shoot all of them?" asked Reggie Jones, 40, father of a 23-year-old son, who attended the march Friday with his wife and daughter.
Even African American churches, where conservatively dressed members typically speak out against the fashions inspired by hip-hop culture, are getting involved in the hoodie protest. On Sunday, more than 30 men at Mount Zion United Methodist Church wore hoodies at their annual Men's Day service in memory of Trayvon Martin.
"We need to stop allowing people to tell us what we can and can't wear," said the Rev. Micah Sims, who helped organize the protest. "It's not about what we wear; it's about who we are."
African American men are arguably the nation's biggest tastemakers. Often, they take a piece of classic American clothing and put a twist on it. And the way they wear it becomes a trend that mainstream America copies.
Hoodies popped into mainstream culture when Sylvester Stallone made them popular in Rocky. But hoodies did not become really cool until hip-hop artists such as Run DMC and the Wu-Tang Clan proudly rocked and rapped about them. Eventually, hoodies came to be featured in every hip-hop clothing line, from Phat Farm to Rocawear.
But what often happens is that while mainstream America gets points for cool, even appropriating the looks for the runway, black men get labeled sinister for wearing the trend they created. Masculine white guys are trendy; masculine black men are feared.
That became more true with hip-hop culture as everything from Timberland boots to white T-shirts to sports jerseys reached the heights of fashion in the black community but also become ways to profile black men.
"We live in a society where people are more likely to assume a young black man is a criminal," said James Peterson, professor of history at Lehigh University.
"It's in our music. In our TV. It's how it's reported on film, video games, and it has fueled certain sartorial prejudices that rear their head in the form of racial profiling."
So black parents find themselves having to tell their children they can't do what everyone else is doing because they will be perceived negatively.
But unlike sagging jeans and tattoos, which often are considered slovenly and threatening, nothing could be more all-American than a hoodie. Not just the uniform of hip-hop, they are preferred apparel at sporting events and as comfort wear. President George W. Bush was often photographed jogging in his.
By the early part of the millennium, they were at their peak, spurred by Pharrell Williams' wearing bright Bathing Ape hoodies and the rise of Juicy Couture.
Fashions change, and slowly but surely hip-hop artists began wearing their hoodies up. As did skateboarders and even Olympic athletes.
But for black men, the hoodie had become criminalized, as did any black man - or teen - wearing one.
"Material culture for other races is tangential," Peterson said. "Unfortunately, material culture for black folks can be life or death."
Contact fashion writer Elizabeth Wellington at 215-854-2704, firstname.lastname@example.org, or follow @ewellingtonphl on Twitter.