More than 100 cities and counties have adopted some form of a growth boundary—a limit on land development beyond a politically designated area—to curb sprawl, protect open space, or encourage the redevelopment of inner-city neighborhoods. Statewide mandates for growth boundaries exist in Oregon, Tennessee, and Washington. Urban-growth boundaries, however, have potentially negative, if unintended, side effects. By reducing the supply of developable land, for example, housing and land prices could increase, reducing housing affordability and production. Local policymakers and citizens need to understand the nature of these tradeoffs and impacts before they adopt growth boundaries.