Drug prohibition violence has painted Monterrey with the look and feel of the gritty border 100 miles (160 kilometers) to the north. This wasn't supposed to happen in Mexico's modern northern city with gleaming glass towers that rise against the Sierra Madre, where students flock to world-class universities, including the country's equivalent of MIT. The deterioration happened nearly overnight, laying bare issues that plague the entire country and speak to the nature of drug prohibition.