The letter, co-signed by leading economists, states: “The rental value of land arises from three sources. The first is the inherent natural productivity of land, combined with the fact that land is limited. The second source of land value is the growth of communities; the third is the provision of public services. All citizens have equal claims on the component of land value that arises from nature. The component of land value that arises from community growth and provision of services is the most sensible source of revenue for financing public services that raise the rental value of surrounding land. These services include roads, urban transit networks, parks, and public utility networks for such services as electricity, telephones, water and sewers. A public revenue system should strive to collect as much of the rent of land as possible, allocating the part of rent derived from nature to all citizens equally, and the part derived from public services to the governmental units that provide those services.”