Transfer of Development Rights (TDR) programs allow local governments to put economic principles to work in encouraging good land use planning. TDR programs most often permit landowners to forfeit development rights in areas targeted for preservation and then sell those development rights to buyers who want to increase the density of development in areas designated as growth areas by local authorities. Although TDR programs must conform to zoning laws, they provide market incentives that make them more equitable (and often more lucrative) for sellers and frequently benefit buyers by allowing them to receive prior approval for their high-density development plans. Since the 1970s when modern TDR applications were first conceived, more than 200 communities in 33 states across the U.S. have implemented TDR-based programs. The most common uses of TDR to date involve protecting farmland, environmentally sensitive land, historic sites, and rural character