Some of the fiercest political battles in the United States are taking place far from the power structure in Washington, D.C. From pocketbook issues like minimum wage to civil rights and paid sick leave, the growing tension between many Democratic-controlled cities and Republican-led state legislatures is now playing out through a political maneuver called preemption, when state lawmakers write laws preempting city regulations. NewsHour Weekend Special Correspondent Chris Bury traveled to Missouri to explain this aspect of the nation's blue-city, red-state divide.