President Barack Obama, delivering a farewell address in the city that launched his political career, declared on Tuesday his continued confidence in the American experiment. But he warned, in the wake of a toxic presidential election, that economic inequity, racism and closed-mindedness threatened to shred the nation's democratic fabric. "We weaken those ties when we define some of us as more American than others," Obama said, "when we write off the whole system as inevitably corrupt, and when we sit back and blame the leaders we elect without examining our own role in electing them."
Speaking to a rapturous crowd that

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