David Card shared the 2021 Nobel Memorial Prize in Economic Sciences for empirical contributions to labor economics, including research on minimum wages.
Card and Alan Krueger famously compared employment at fast-food restaurants in New Jersey and Pennsylvania after New Jersey raised its minimum wage in 1992. Their difference-in-differences study challenged the simple prediction that a higher minimum wage must reduce employment.
The research helped strengthen the use of natural experiments in economics, where policy changes or other external events create comparison groups. Card’s broader work also studied immigration, education, and labor-market outcomes.
Card shared half of the 2021 prize, while Joshua Angrist and Guido Imbens shared the other half for methodological contributions to causal analysis. Alan Krueger co-authored the minimum-wage study but was not a 2021 laureate.