LOS ANGELES—Demonstrators waving union banners and American flags took to the streets of downtown Los Angeles Sunday for May Day marches calling for immigration reform and workers' rights. The biggest march, organized by the Coalition for Humane Immigrant Rights of Los Angeles, began at noon and moved northbound on Broadway from Olympic Boulevard. It ended with a rally at 1st Street featuring dancers, musicians and speakers from labor and community groups....

Thousands of demonstrators march during a May Day immigration rally on May 1, 2010, in Los Angeles.