In this paper we study the effect of price floor regulations on the organization and performance of markets. The standard interpretation of the effects of these policies is concerned with short-run market distortions associated with excess supply. Since price controls prevent markets from clearing, they lead to higher prices. While this analysis may be correct in the short-run, it does not consider the dynamic equilibrium consequences of price controls. We demonstrate that price floor regulations can have important long-run effects on the the structure of markets by crowding them and creating endogenous barriers to entry for low-cost retailers. Moreover, we show that these factors can indirectly lower productiviTY and possibly even prices. We test this in the context of an actual regulation imposed in the retail gasoline market in the Canadian province of Québec and show that the policy led to more competition between smaller/less efficient stations. This resulted in lowered sales, and, despite the reduction in efficiency, did not increase prices.