Voting can be done at the ballot box, but people often "vote with their feet," making choices about where to live. "Foot voting" happens by international migration, by choosing where to live within a federal system, and by making decisions in the private sector. In his new book, Free to Move, Ilya Somin explains how broadening opportunities for foot voting can greatly enhance political liberty for millions of people around the world. Somin contends that all forms of foot voting should be expanded and shows how both domestic constitutions and international law can be structured to increase opportunities for foot voting while mitigating possible downsides.