Martin, a 17-year-old African-American, was killed on February 26 while walking in a gated community in Sanford, Florida by George Zimmerman, a neighborhood watch volunteer.
Sanford police did not charge Zimmerman after he said he shot Martin in self-defense. A grand jury, however, will decide whether to charge Zimmerman with murder on April 10.
Civil Rights activist Jesse Jackson on Sunday told people at a church in Eatonville, Florida that the murdered teen, Trayvon Martin, is a "martyr."
Thousands of protesters rallied across the US in a show of anger against the shooting death of an African-American teenager in the state of Florida.
Chanting "no justice, no peace," in different US cities including Washington D.C., Chicago, Tampa and Nashville, protesters dressed in black hooded sweatshirts, like the one Martin was wearing when he was shot, demanded justice and prosecution of his killer.
Protesters, mainly African-Americans, say the killing manifests the unjust treatment of the large black community in the country.
Critics also say the murder was racially motivated. Trayvon's case has stirred serious concerns over racial discrimination against the African-American community in the US.