Most large cities of the world's most affluent countries are increasingly unaffordable in ways that raise serious normative questions. The price of purchasing and renting housing is relatively high due to political constraints on supply. These constraints do not protect the normative interests of residents of these cities, and generate a system in which development that would be mutually beneficial is prohibited. I argue that rights over commonly used urban space have the same liberty-based justification as traditional private property rights. (...) And that assigning rights over the disposition of common space to those most local to it, to use, develop, or transfer as they collectively wish, would overcome the problem. It would do so by enabling an expansion of housing supply where it is most needed, but only through a procedure that ensures it will benefit local residents, by their own lights. (shrink)