This is the procession commemorating Ashura, or the 10th of Moharram. In front, you can see a painstakingly recreated model of the tomb of Husain. The mourners are dressed mostly in black. It is a testament to the tolerance of American society that despite the best attempts of some of its cleverest citizens to proclaim a "clash of civilizations," it allows (and observes with curiosity) such displays of foreign sentiment.