Adapting to the Weather: Lessons from U.S. History.

An important unknown in understanding the impact of climate change is the scope of adaptation, which requires observations on historical time scales. We consider how weather across U.S. history (1860-2000) has affected various measures of productivity. Using cross-sectional and panel methods, we document significant responses of agricultural and individual productivity to weather. We find strong effects of hotter and wetter weather early in U.S. history, but these effects have been attenuated in recent decades. The results suggest that estimates from a given period may be of limited use in forecasting the longer-term impacts of climate change.

Shocking Behavior: Random Wealth in Antebellum Georgia and Human Capital Across Generations.

Does the lack of wealth constrain parents' investments in the human capital of their descendants? We conduct a nearly fifty-year followup of an episode in which such constraints would have been plausibly relaxed by a random allocation of substantial wealth to families. We track descendants of participants in Georgia's Cherokee Land Lottery of 1832, in which nearly every adult white male in Georgia took part. Winners received close to the median level of wealth - a large financial windfall orthogonal to participants' underlying characteristics that might have also affected their children's human capital. Although winners had slightly more children than non-winners, they did not send them to school more. Sons of winners have no better adult outcomes (wealth, income, literacy) than the sons of non-winners, and winners' grandchildren do not have higher literacy or school attendance than non-winners' grandchildren. This suggests only a limited role for family financial resources in the formation of human capital in the next generations in this environment and a potentially more important role for other factors that persist through family lines.

Thick-Market Effects and Churning in the Labor Market: Evidence from U.S. Cities.

Using U.S. Census microdata, we show that, on average, workers change occupation and industry less in more densely populated areas. The result is robust to standard demographic controls, as well as to including aggregate measures of human capital and sectoral mix. Analysis of the displaced worker surveys shows that this effect is present in cases of involuntary separation as well. On the other hand, we actually find the opposite result (higher rates of occupational and industrial switching) for the subsample of younger workers. These results provide evidence in favor of increasing-returns-to-scale matching in labor markets. Results from a back-of-the-envelope calibration suggest that this mechanism has an important role in raising both wages and returns to experience in denser areas.

Portage and Path Dependence.

We examine portage sites in the U.S. South, Mid-Atlantic, and Midwest, including those on the fall line, a geomorphological feature in the southeastern U.S. marking the final rapids on rivers before the ocean. Historically, waterborne transport of goods required portage around the falls at these points, while some falls provided water power during early industrialization. These factors attracted commerce and manufacturing. Although these original advantages have long since been made obsolete, we document the continuing importance of these portage sites over time. We interpret these results as path dependence and contrast explanations based on sunk costs interacting with decreasing versus increasing returns to scale.

Age at Arrival, English Proficiency, and Social Assimilation Among U.S. Immigrants.

Are U.S. immigrants' English proficiency and social outcomes the result of their cultural preferences, or of more fundamental constraints? Using 2000 Census microdata, we relate immigrants' English proficiency, marriage, fertility and residential location variables to their age at arrival in the U.S., and in particular whether that age fell within the "critical period" of language acquisition. We interpret the differences between younger and older arrivers as effects of English-language skills and construct an instrumental variable for English-language skills. Two-stage-least-squares estimates suggest that English proficiency increases the likelihood of divorce and intermarriage. It decreases fertility and, for some, ethnic enclave residence. (JEL J24, J12, J13, J61).

Health, Human Capital, and Development.

How much does disease depress development in human capital and income around the world? I discuss a range of micro evidence, which finds that health is both human capital itself and an input to producing other forms of human capital. I use a standard model to integrate these results, and suggest a re-interpretation of much of the micro literature. I then discuss the aggregate implications of micro estimates, but note the complications in extrapolating to general equilibrium, especially because of health's effect on population size. I also review the macro evidence on this topic, which consists of either cross-country comparisons or measuring responses to health shocks. Micro estimates are 1-2 orders of magnitude smaller than the cross-country relationship, but nevertheless imply high benefit-to-cost ratios from improving certain forms of health.

Malaria Eradication in the Americas: A Retrospective Analysis of Childhood Exposure.

This study uses the malaria-eradication campaigns in the United States (circa 1920), and in Brazil, Colombia and Mexico (circa 1955) to measure how much childhood exposure to malaria depresses labor productivity. The campaigns began because of advances in health technology, which mitigates concerns about reverse causality. Malarious areas saw large drops in the disease thereafter. Relative to non-malarious areas, cohorts born after eradication had higher income as adults than the preceding generation. These cross-cohort changes coincided with childhood exposure to the campaigns rather than to pre-existing trends. Estimates suggest a substantial, though not predominant, role for malaria in explaining cross-region differences in income.

Chronic Disease Burden and the Interaction of Education, Fertility, and Growth.

This study considers the eradication of hookworm disease from the American South as a test of the quantity-quality (Q-Q) framework of fertility. Eradication was principally a shock to the price of quality because of three factors: hookworm (i) depresses the return to human-capital investment, (ii) had a very low case-fatality rate, and (iii) had negligible prevalence among adults. Consistent with the Q-Q model, we find a significant decline in fertility associated with eradication. Relative sizes of fertility and human-capital responses to hookworm indicate that the Q-Q mechanism is of a similar magnitude to secular co-movements in these same variables.

Economic Effects of Childhood Exposure To Tropical Disease.

To what extent do tropical diseases contribute to the poverty characteristic of tropical countries? Estimates of the impact of health on income are difficult to obtain because health is a normal good-countries with higher income will buy more of it-and third factors such as remoteness and bad government might impede both productivity and public health. In the Abuja Declaration of 2005, African heads of states claim that malaria has depressed income growth in Subsaharan Africa since the 1960s, so much so that GDP in the region today is 40% lower because of malaria. Estimates of this magnitude have been mocked at cocktail parties and clambakes. But how ridiculous is this number?

What Holds Back the Second Generation? The Intergenerational Transmission of Language Human Capital Among Immigrants.

In 2000 Census microdata, various outcomes of second-generation immigrants are related to their parents' age at arrival to the United States, and in particular whether that age fell within the "critical period" of language acquisition. We interpret this as an effect of the parent's English-language skills and construct an instrumental variable for parental English proficiency. Estimates of the effect of parent's English-speaking proficiency using two-stage least squares yield significant, positive results for children's English-speaking proficiency and preschool attendance, and significant, negative results for dropping out of high school and being below age-appropriate grade. (JEL J13, J24, J62).

Disease and Development: Evidence from Hookworm Eradication in the American South.

This study evaluates the economic consequences of the successful eradication of hookworm disease from the American South. The hookworm-eradication campaign (c. 1910) began soon after (i) the discovery that a variety of health problems among Southerners could be attributed to the disease and (ii) the donation by John D. Rockefeller of a substantial sum to the effort. The Rockefeller Sanitary Commission (RSC) surveyed infection rates in the affected areas (eleven southern states) and found that an average of forty percent of school-aged children were infected with hookworm. The RSC then sponsored treatment and education campaigns across the region. Follow-up studies indicate that this campaign substantially reduced hookworm disease almost immediately. The sudden introduction of this treatment combines with the cross-area differences in pre-treatment infection rates to form the basis of the identification strategy. Areas with higher levels of hookworm infection prior to the RSC experienced greater increases in school enrollment, attendance, and literacy after the intervention. This result is robust to controlling for a variety of alternative factors, including differential trends across areas, changing crop prices, shifts in certain educational and health policies, and the effect of malaria eradication. No significant contemporaneous results are found for adults, who should have benefited less from the intervention owing to their substantially lower (prior) infection rates. A long-term follow-up of affected cohorts indicates a substantial gain in income that coincided with exposure to hookworm eradication. I also find evidence that eradication increased the return to schooling.