Abstract: The purpose of this study is to analyze the evolution of city size distribution over time for a regional urban system. The evolution of cities and towns in Indian state is studied: Kerala for the period of 1951-2001. The cross-sectional distribution of urban population growth process is modeled as a first order stationary Markov chain. Based on the methodology two main results are obtained. First, intradistribution movements have taken place in the ranking of cities and towns during the period of 1951-2001. Secondly, this evolution has not been homogeneous, with a divergent pattern of growth for the entire data relating to the regional city size distribution. The research framework proposed and utilized here is able to portray the movements of cities and towns of a regional urban system and the framework can be used to evaluate regional urban policies for the economic development of the region.