Migration, Internal Population 13 Emigration and immigration 12 Labor mobility 12 Social conditions 12 History 9 Labor supply 7 Rural-urban migration 7 Urbanization 7 Cities and towns 6 Economic conditions 6 Migrant labor 5 Rural conditions 5 Case studies 4 Government policy 4 Mathematical models 4 Congresses 3 Economic aspects 3 Education 3 Land settlement 3 Regional planning 3 Social mobility 3 Working class 3 Agricultural laborers 2 Agriculture 2 Alien labor 2 Demography 2 Growth 2 Housing 2 Industrial location 2