November 2020, Paper: "Beginning in 1951, the Conference Board constructed a monthly job vacancy index by counting the number of help-wanted ads published in local newspapers in 51 metropolitan areas. We use this Help-Wanted Index (HWI) to document how immigration changes the number of job vacancies in the affected labor markets. Our analysis revisits the Mariel episode. The data reveal a sizable drop in Miami’s HWI relative to comparable cities in the first 4 or 5 years after Mariel, followed by recovery afterwards. We also examine the text of the help-wanted ads published in a number of newspapers and document a significant post-Mariel decline in the relative number of low-skill vacancies advertised in the Miami Herald. The post-Mariel trends are consistent with the observed relation between immigration and the HWI across all metropolitan areas in the 1970-2000 period: the spatial correlation suggests that more immigration reduces the number of job vacancies. We explore some of the macroeconomic implications and show that Miami’s Beveridge curve shifted inwards by the mid-1980s, suggesting a more efficient local labor market, in contrast to the outward nationwide shift coincident with the 1981-1982 recession."