Michel Martin

This Tuesday's Mardi Gras celebration in New Orleans has thrust into the spotlight a controversial local tradition dating back more than 100 years.

Every year, members of the city's Zulu Social Aid and Pleasure Club don grass skirts, feather headdresses and bone jewelry for the Mardi Gras parade.

The Zulus' African-American members — and even some of their white members — also paint their faces black.

A small moment of anger pushed Grammy-winning artist Gary Clark Jr. to create the unapologetic, seething song "This Land."