The legalization of marijuana has spread rapidly throughout the United States, from just a handful of states ten years ago to now more than half, as well as the nation's capital. In Canada, it is legal to use and distribute nationally. Thousands of cities and towns are following suit.

Legalization seems to be a win-win--people who use cannabis for health and recreation are served, business is brisk, and many governments welcome the much-needed boost in tax revenue. But not everyone thinks so. The rapid pace of legalization has spurred debate among citizens, cities, states and the federal government. This collection of essays explains the benefits and concerns, the policies and actions, and the future of this controversial issue.