Job Vacancies and Immigration: Evidence from Pre- and Post-Mariel Miami. George Borjas, May 2018, Paper, “How does immigration affect labor market opportunities in a receiving country? This paper contributes to the voluminous literature by reporting findings from a new (but very old) data set. 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 the Help-Wanted Index (HWI) to document how immigration changes the number of job vacancies in the affected labor markets. Our analysis begins by revisiting the Mariel episode.Link