“The nation should face up to two facts: poverty rates are too high, especially among children, and spending money on government means-tested programs is at best a partial solution,” Ron Haskins of the Brookings Institution wrote in an assessment of the shortfalls on the war on poverty. Washington already spends enough on antipoverty programs to lift all Americans out of poverty, he said. “To mount an effective war against poverty,” he added, “we need changes in the personal decisions of more young Americans.”

Still, a broad range of researchers interviewed by The New York Times stressed the improvement in the lives of low-income Americans since Mr. Johnson started his crusade. Infant mortality has dropped, college completion rates have soared, millions of women have entered the work force, malnutrition has all but disappeared. After all, when Mr. Johnson announced his campaign, parts of Appalachia lacked electricity and indoor plumbing.

Many economists argue that the official poverty rate grossly understates the impact of government programs. The headline poverty rate counts only cash income, not the value of in-kind benefits like food stamps. A fuller accounting suggests the poverty rate has dropped to 16 percent today, from 26 percent in the late 1960s, economists say.