The Haiti earthquake of January 2010 exposed vulnerabilities in Port-au-Prince that made the disaster especially catastrophic. Urbanization in Haiti followed patterns similar to that elsewhere, but unique economic patterns and lack of construction regulations placed the inhabitants of Port-au-Prince in special danger. Migration to the capital intensified under the Duvalier regimes and weaknesses in institutional capacity created unsafe conditions. Agricultural policies and continued high birth rates exacerbated density, adding to high casualties and displacement. This article examines the nature of Haitian vulnerability and surveys literature describing historical influences, beginning in the nineteenth and twentieth centuries, that contributed significantly to creating the tragic situation resulting from the earthquake.