The Mariel Boatlift Debate: Card's No-Effect Finding vs. Borjas's Reanalysis
The 1980 Mariel Boatlift serves as one of the most famous natural experiments in labor economics. Over a period of just a few months, approximately 125,000 mostly low-skilled Cuban refugees arrived in Miami, increasing the city's overall labor force by 8% and its low-skill workforce by an estimated 20%. Because this labor supply shock was sudden, exogenous, and concentrated in a single metropolitan area, it became the premier testing ground for how low-skilled immigration affects native wages and employment.
David Card's Seminal Study (1990)
In 1990, economist David Card published a highly influential study analyzing the impact of the boatlift. Card compared labor market outcomes in Miami to a control group of four other cities (Atlanta, Los Angeles, Houston, and Tampa-St. Petersburg) that had similar employment trends. He defined "low-skilled workers" broadly as those with a high school education or less. Card's analysis found no statistically significant negative effects on either the wages or unemployment rates of native-born workers or earlier Cuban immigrants.
George Borjas's Reappraisal (2015/2017)
In 2015, Harvard economist George Borjas published a reappraisal of Card's study, arguing that Card's broad definition of "low-skilled" (high school or less) masked the negative impacts on the most vulnerable subgroup: high school dropouts (those with less than a high school education). By isolating non-Hispanic prime-age males with less than a high school education, Borjas identified a massive wage contraction in Miami relative to a control group of cities (Anaheim, Rochester, Nassau-Suffolk, and San Jose). Borjas concluded that the boatlift had caused a severe decline in native wages for this specific, narrow skill group.