Why do people live where they live and what are the consequences of these decisions? People and firms allocate themselves unevenly across space. In spite of large costs incurred when living in metropolitan areas, economic agents remain extremely concentrated in a finite number of cities. This thesis explores several factors that may influence these location decisions and their effect on economic agents. The first essay questions the role of cultural amenities in explaining the location of firms and residents across American cities. Next, the second essay examines a consequence of the geographic concentration of workers. It evaluates the influence of urban density on the quality of the match between workers' education and their occupation. Finally, the last essay documents the importance of housing vacancies in France. It examines how distance and access to the city center affect the housing vacancy rate in suburban municipalities.