Catherine Lejeune is a lecturer in American Studies at the Université Paris Cité, and a member of LARCA, UMR 8225 (Research Laboratory on Anglophone Cultures). Her area of specialisation is the history and evolution of the US migration system, in particular the growing role of local immigration policies. Her recent research lies at the intersection of migration studies and urban studies, and focuses on the manufacture of diversity in global cities. She studies irregular migrants as emerging actors in urban diversity in the United States, particularly in sanctuary cities. From 2014 to 2018, together with Delphine Pagès-El Karoui (CERMOM, Inalco), she coordinated the 'Villes-mondes et Migrations' section of the interdisciplinary 'Sociétés Plurielles' programme, in particular the MAGMET (Migrants in Global metropolises) research seminar.