Ruby Duncan, one of the most effective advocates for Nevada’s poor and racially oppressed, has died. She was 93. She won national fame in the 1970s by organizing a welfare rights march that temporarily halted gambling at Caesars Palace, then the plushest casino on the Strip. Duncan also was a founder of the anti-poverty agency Operation Life and helped establish a medical clinic in the heart of Las Vegas’ impoverished West Side. Duncan died at Spring Valley Hospital on Sunday morning, according to her granddaughter Libra Duncan. Duncan was born in poverty June 7, 1932, near Tallulah, Louisiana, the daughter of sharecroppers. Her parents died before she was 4 years old, and she grew up in the homes of relatives. She and other black children worked the fields of white-owned Ivory Plantation from May through October every year. They attended school from November through April, a shorter school year than was provided for white children.…