Floating population: migration with(out) family and the spatial distribution of economic activity ∗ Cl ement Imbert Joan Monras Marlon Seror ́ Yanos Zylberberg January 24, 2025 Abstract A key, yet under-explored, aspect of migration is the decision to leave behind dependent family members. We develop and estimate, using Chinese data, a quanti- tative spatial model in which rural workers choose whether to migrate, whether to bring their family, where to go, and how to allocate their consumption across house- hold members and across space. The general-equilibrium model rationalizes the fact that rural migrants disproportionately move to expensive, unwelcoming cities, live without their family, and send remittances. We quantify the role of migration fric- tions in explaining these patterns and show that, by changing the relative value of consumption across space, they contribute to the rise of non-family migration and the emergence of mega-cities.