Democracy, Division, and the Declaration at 250

America is turning 250. The country's birthday arrives amid a war with Iran, soaring prices and a firestorm of political polarization. As America looks inward at its history and its future, how is a unified celebration possible? Jill Lepore is an American historian and author of "We the People." She discusses this and looks back at the country's history — the good, the bad and the ugly.