This chapter shows that new georeferenced databases can help consolidate the geographical scope of historical studies of transport networks, due to their capacity to integrate data relating to various themes, and provide relevant analyses. It presents the indicators that people have developed to analyse both the network itself and its interrelationship with population. The chapter examines historical databases that provide information about railroads and population in Europe from a national and historical perspective. It explains the most significant work that has been undertaken in order to try to quantify the impact of the railroad network on population and urbanization. First approximation to railroad databases at the European scale can be found within the framework of the historical geographic information system project. The main indicators used to refer to population are its territorial distribution, whether expressed in absolute terms or as density per unit area, and its percentage increases, which are always contemplated at ten-year intervals.