In the United States we celebrate Halloween. Why? I don't really know the history behind the holiday.
In Mexico, on November 1st, Day of the Dead is celebrate. Apparently its a big deal, with alters, food and celebrations and ceremonies. I have never been so I can't say much more.
But in El Salvador, Day of the Dead is celebrate on November 2nd. All Souls Day. Salvadorans all make the trek to the cemetery to enflorar or put flowers and clean up the graves of their loved ones.
But some Salvadorans aren't so lucky to have graves for their loved ones. A 12 year Civil War left 75,000 dead or disappeared.