Thompson said the veterans didn't have specific permission to raise the Gadsden flag, but they never needed specific permission to raise the Stars and Stripes on city property, either.

WSJ: City: No 'Don't Tread on Me' flag on public land

Early on, it was mostly young Mexican-Americans, people born in the U.S., who carried the Mexican flag, and it was mostly immigrants, the people from Mexico, who carry the stars and stripes.

NPR: Coordinating Flags at Immigration Marches