Rural-urban interaction is largely determined by nature and the effort needed to bridge distances between cities. With simple words, without cities there would be no rural areas, space would be divisible and people would not move. The difference between living in a city and living in rural areas is less transport efforts in cities, scale economies, and the “love for variety effect.“ Besides food consumption, urban dwellers can choose from a larger variety of substitutable manufactured goods; and this constitutes an urban amenity. Even though modern technology may help rural areas to bridge that gap, the natural rural-urban divide remains. By augmenting the ubiquitous law of city rank-sizes in a model with spatial disturbance it can be shown that there are modest but significant inter-city distance effects in the evolution of such national city systems.