ABSTRACT
Population counting, its control and management, and border security, are issues in the contemporary political and social debate where demographics are used to justify different policies. The availability of suitable data will facilitate studies on mobility, generally defined as change in space, and on migration, that is, the movement of people across a specified boundary to establish a new residence. The potential uses and misuses of data encourage further discussion and attention to the ways to collect and process field data. The chapter focuses on sources to address the study of migration in demography after reviewing the relationship between territory and population. New international migrations, new communication systems, new financial flows and new political entities constitute relationships that cross, fluidize and shape borders, reshaping the model of the coincidence between territory and population.
