Casper Worm Hansen

University of Copenhagen
Øster Farimagsgade 5
Copenhagen, Denmark

Institutional Affiliation: University of Copenhagen

NBER Working Papers and Publications

December 2019The Effects of Immigration on the Economy: Lessons from the 1920s Border Closure
with Ran Abramitzky, Philipp Ager, Leah Platt Boustan, Elior Cohen: w26536
In the 1920s, the United States substantially reduced immigrant entry by imposing country-specific quotas. We compare local labor markets with more or less exposure to the national quotas due to differences in initial immigrant settlement. A puzzle emerges: the earnings of existing US-born workers declined after the border closure, despite the loss of immigrant labor supply. We find that more skilled US-born workers – along with unrestricted immigrants from Mexico and Canada – moved into affected urban areas, completely replacing European immigrants. By contrast, the loss of immigrant workers encouraged farmers to shift toward capital-intensive agriculture and discouraged entry from unrestricted workers.
May 2019Controlling Tuberculosis? Evidence from the First Community-Wide Health Experiment
with Karen Clay, Peter Juul Egedesø, Peter Sandholt Jensen, Avery Calkins: w25884
This paper studies the immediate and long-run mortality effects of the first community-based health intervention in the world – the Framingham Health and Tuberculosis Demonstration, 1917-1923. The official evaluation committee and the historical narrative suggest that the demonstration was highly successful in controlling tuberculosis and reducing mortality. Using newly digitized annual cause-of-death data for municipalities in Massachusetts, 1901-1934, and different empirical strategies, we find little evidence to support this positive assessment. In fact, we find that the demonstration did not reduce tuberculosis mortality, all-age mortality, nor infant mortality. These findings contribute to the ongoing debate on whether public-health interventions mattered for the decline in (tuberculo...

Published: Karen Clay & Peter Juul Egedesø & Casper Worm Hansen & Peter Sandholt Jensen & Avery Calkins, 2020. "Controlling tuberculosis? Evidence from the first community-wide health experiment," Journal of Development Economics, vol 146.

April 2019How the 1906 San Francisco Earthquake Shaped Economic Activity in the American West
with Philipp Ager, Katherine Eriksson, Lars Lønstrup: w25727
This paper examines the long-run effects of the 1906 San Francisco Earthquake on the spatial distribution of economic activity in the American West. Using variation in the potential damage intensity of the earthquake, we show that more severely affected cities experienced lower population increases relative to less affected cities until the late 20th century. This long lasting effect is largely a result of individuals’ high geographical mobility at that time. Less affected areas became more attractive migration destinations in the immediate aftermath of the earthquake, which permanently changed the spatial distribution of economic activity in the American West.
June 2018Two Blades of Grass: The Impact of the Green Revolution
with Douglas Gollin, Asger Wingender: w24744
We examine the economic impact of high-yielding crop varieties (HYVs) in developing countries 1960-2000. We use time variation in the development and diffusion of HYVs of 10 major crops, spatial variation in agro-climatically suitability for growing them, and a differences-in-differences strategy to identify the causal effects of adoption. In a sample of 84 counties, we estimate that a 10 percentage points increase in HYV adoption increases GDP per capita by about 15 percent. This effect is fully accounted for by the direct effect on crop yields, factor adjustment, and structural transformation. We also find that HYV adoption reduced both fertility and mortality.
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